I have personally killedseveral deer off my 4 wheeler and out of my Mule. I hunt a unique600 acre tract that has subdivisions on 3 sides and a creek bottom and railroad on the other side. My deer are used to human activity and don't pay much attention to ATVs (but when you step off, they are gone). I believe it depends on the place and the deer. If the only ATV activity the deer see is during hunting season, they are probably going to be very leary of them.But if youare on a place year around riding ATVs, then the deer willprobably never pay them any attention.