A general review of microwave engineering problems of the microwave oven is presented. Of central importance is the continuing improvement of the microwave magnetron in efficiency and stability. The goal of uniform heating is discussed with reference to measurement techniques and efforts at standardization. Advances in door-seal techniques are presented with reference to leakage and RFI requirements. Lastly the relevance of the basic microwave problems in the microwave oven to other ISM applications is discussed.