Karin

To me, the obvious recomendation is the anime KARIN, also about a high school boy and a vampire girl. While KARIN for the most part lacks the "fighting" elements of ROSARIO+VAMPIRE, the romantic comedy elements of a supernatural "odd-couple" remain.  

Both of the main character is a vampire and the boy in both story are human and got stuck with the main character.  

These stories tell how boys somehow got involved in vampires, the main characters. Karin is a reverse vampire though giving blood instead of taking. Rosario has more fighting scenes and more like harem. 

both have a vampire girl that needs to suck blood from the guy protag. of course the guy is a regular dude, but he gets pulled into the whole vampire zone (though in RV it also includes other demons) 

Both have the main characters being a vampires that also go to school...The vampires also are supposed to hide that fact that they are vampires.  

Both of the main character is a vampire and the boy in both story are human and got stuck with the main character. 

Both have vampires, love rivals, and are both but together with a large amount of care. Two of my favorite shows ever! Both also have a large variety of different interesting characters. 

Both anime follow the daily life of normal boys who suddenly fall in love with a girl that happens to be a vampire. Comedy ensured when they become friends. The only difference in Rosario to Vampire is that there is more of a harem. I recommend this to everyone who's searching for some comedy/action to kill time. 

Both have a female lead characters whom are quite dense. Both these rom/coms have a school setting where the main characters (Tsukune/Karin) are trying to hide the fact about their identities while trying to lead a 'normal' life. Both are hilarious and are worth a watch if you are a fan of rom/coms. Rosario though does have more fighting scenes and has a harem while Karin is mainly focused around Karin and her secret (reverse vampire) and realisation of love for Kenta. 

So if you're searching for an anime wich includes vampires and romance, this is just what you're looking for, and this is because if even both of the series share some factors in common they also have inversed roles, a totally fresh story that talks about how a vampire family and her sons live in a world of humans, the totally opposite of rosario to vampire, but this change makes some of the scenes on the show very similar to the ones in rosario to vampire but with inverse roles. I hope you give it a chance if this sounds interesting to you. 

Not quite the same but it also involves human vampire love. Karin is more comedy oriented. 

Vampires are alive and thriving, even tho normal humans dont know it. What they also dont know is that not all Vampires are evil, some go way beyond that, and some are really funny ^^ Vampires, friends or foe? decide for yourself while watching this! 

They both involve vampires and blood, (But not in a violent and gorey way.) Also there is love between the main characters. =] 

both animes are revolved around vampires with the female leads falling in love with someone they 'arn't suppose to'. although the seriousness of the animes are completely different (with Karin being more carefree and light & Vampire Knight being more serious) they are both very good animes! 

Both have to do with vampires. Also they both have there share of action, romance, comedy , and basic good storyline. They are two very good anime! 

if you like the Vampire genre, you might as well try Karin. Karin has the Vampire genre with romance just like Vampire Knight. Vampire Knight has a serious atmosphere while Karin is a love-comedy show. 

Vampire stories with Romancee ~ Vampires and Humans are trying to get along with each other. Human and Vampire fall in love. Kind of the same setting; mostly takes place in a school. Karin is trying to become a real vampire, while Yuuki becomes a pure blood vampire. 

They are both romance anime involving vampires. However, Karin is more of a light-hearted romantic comedy while Vampire Knight is dark and serious. Both involve the hope that humans and vampires will one day be able to co-exist peacefully. 

Both Series Have A Girl Character Who Wants To Live In A World Where Vampires And Humans Can Exist. They also Both Have Secrets. Both Main Characters, (Yuuki From Vampire Knight, And Karin From Karin) Have Similar Traits In Their Personality. 

Both anime are about cute unusual vampire girls trying to live there lives. 

Both have a vampire girl that is in her own way special.Both have these vampires falling in love with a human boy 

both have vampires karin is more cheery though. but still has the same feel to it. 

It's hard to take these two serious especially when the main female character (who happens to be a vampire in both series) is presented in a moe and cute way. Both series explores the relationship between a vampire and a normal human who shares a special (and often comedic) bond. Both series has romance but at the same time has many comedic and dramatic scenes. However at times, there are also emotional moments especially involving the dynamic duo of the two main characters in both series. 

Comedy series where a cute vampire girl falls in love with a normal human guy.  

a normal guy meets a girl and get thrown into the world of vimpires 

Both heroines are vampires and both protagonist found out and have to keep their secret and their is also something special about them. i dont know whether this anime is good yet but if you liked karin then maybe you'll like it  

karin is like an upgrade to fortune arterial, it has everything that fortune has, but 10 times more of it, literally. plot, character, development, romance, you name somthing fortune has, karin has a better version of it (and yes that includes vampires) if u liked fortune or u just want a better version of it, I highly HIGHLY recommend karin. 

It`s a little similar, because Usui in kaichou wa maid sama holds a secret about Misaki being a maid at a maid cafè. Misaki is kinda emberassed about working there, because she actually is a the most talented girl in the school. 

Karin and Fruits Basket are similar in the sense that they're both "cutesy" funny, and semi-loved up. As Karin is an awkward school girl, so is Torhu Honda, and they seem to go through...not exactly similar difficulties, but have similar dramatic reactions, making for an excellent watch. I found that the Fruits Basket series left me hanging, considering the episode numbers vs manga numbers. But with Karin, I was very happy about the ending actually having an "ending" where show came to a close.<br / Also, to begin with, Karin wasn't something I thought I'd get into, but after the first episode I was hooked. 

Rom-com anime with vampiric main heroines trying to live a normal high school life but the MC accidentally found out about their secret. Hilarity ensues.