I do ... Well most of the time. I know that I should all of the time, but I think that I get so comfortable in my summit viper climber that sometimes I don't use it. If i'm tired I do, and I will if it's windy out I do. This year though...everytime I hunt I will have it on. Too many times I have read of hunters falling out of there stands and dieing because of it. So 2009-2010 hunting year will have a harness on at all times.