Do you mean the length of one period or are you asking how long until your periods stop completely? Usually by the third shot (9 months) your periods should stop. Mine stopped right after my second shot.

i only had one shot, my period stayed on for 1 1/2 months. i got tired of the depo and i also had bad symptoms like i was always hungry, i would feel fatigue when i dont eat and really sick.
i didnt like the way they made me feel. so i was put on a combination birth control and after 4 days of the pill my period stopped.
i gained a lot of weight also.
that's why i dont like the depo, the doctor doesnt tell you the side effects, and tell the patient about how long your period could stay on in the beginning. they dont tell you that you should take calcium because the shot destorys your bones.

i hate depo i only had one shot of it but it screwed my system completely! i had my period for a straight month then 2 weeks of nothing then another month of period so on and so on .... but once itcompletely got out of my system that year i got pregnant ... so it will be awhile to know if my system is right yet

I'm sorry you had such a bad experience on Depo, ServiceU and MrCuevas463. I had a very good experience on it and was fortunate enough to have a great gynecologist that warned me about all the side effects and the shot's effects on the bones. I was on it twice and both were fine. I went off it the first time because I had sworn off sex for a long time. lol And the second, most recent time I quit because I am considering having a child in the future and I know it can take a while for fertility to return. My last shot was in July of last year, my periods resumed in February of this year and I have been right as rain.

it took a full year for it to get out of my system ... i only know this b/c my first shot was november of 2007 and i got pregnant november of 2008 lol

so good luck on making baby!

well i am not too sure if your doctor told you that the symptoms are different. some would bleed through out their whole shot and some won't bleed at all. well i was on that for five years and i had bad symptoms from it. i was gaining so much weight, my hair was falling out, breaking out with pimples really bad, getting bad back aches and headaches. then when i finally got off the depo. it took my boyfriend and i about two and a half years to finally get pregnant but unfortunately i lost the baby and then it took us about seven years to finally have a baby. so if you are experiencing any of these my advice is to get off it...

ckak,
i thought the people that stayed on the shot for a long time was the one's that didnt have any side effects.
so why did you stay on the shot so long if you had horrible side effects?
my hair was falling out also, and i couldnt figure out why. i didnt even want to get on the depo shot my doctor tricked me. i was in the hospital and they just woke me up after my surgery (i was still out of it) and my doctor told them i wanted depo. i was so tired to say "no i dont" we discussed it, and he told me to sleep on it and give him a decission the next day, which was the day of my surgery. so i had to deal with it for three months.
i had too many friends who had bad experiences, so i wasnt willing to try it.