A:AnswerThis is just my "opinion". If you are going to mount over your range and you want to use the exhaust fan function , then yes it must be vented. If you are not going to use the exhaust fan function, then you would not need to vent the microwave. We use the exhaust fan and it works great. Wish I had done some more research on lighting feature. They do not light up the top of my range as bright as I expected. I am researching different or brighter lighting options. Hope this helps!