Ummmm I usually clean the door (inside of it) weekly and give it a bit of a going over with my enjo weekly as well. A full-on clean about quarterly (and I do the inside of the air filter thingy above the stovetop at the same time). I don't use commercial cleaners so find it easier to do it often. If I have any citrus fruit starting to go off (lemons / limes / grapefruit) then I'll do it earlier.