Well, I don't have the time anymore, but around 2 years ago I watched Eureka Seven from episode 12-50 and that was around 15 hours.

Well, that depend on what anime it is... So far the hours I have watch was up to 5 or 10 hours... Cause why waste all those time when you can get-up and get some fresh air outside...

When i first started watching Naruto Shippuden, i was 21 one episodes behind so i watched episodes 1-21 in one sitting.

I went almost two days watching all of blood+ and half of xxxholic only taking breaks to use the bathroom and eat, I know its not something to be proud of but i couldn't stop watching

Last Exile Marthon From 1am-1pm....:)

Here's CHI!
 

Umm How long You have watched anime In one sitting Umm...
Ouran High School Host Club episodes 1-19 all in 1 DAY!!!:rheart:

I was really sick during the summer and watched like 18 episodes of Death Note on top of the entire fruits baskets series. I slept a little bit but the sickness kept me awake so I used the animes to keep me up...totally worth it :p :) My two faves so far

I once watched on youtube naruto for 3 hours straight :D

The most I've done is watch an entire 26 episode series in one sitting, from night until morning...about 11 hours or so probably. Can't believe some of you went for 24 hours or more though. I don't know if I could possibly be intrigued THAT greatly to spend so much time in one position D¦

The whole Outlaw Star series, it took me all day, with breaks for needless things such as food.