Ene reactions involving carbonyl enophiles have been carried out under microwave irradiation at controlled temperature and atmospheric pressure. The reactions of diethyl mesoxalate with 1-decene and beta-pinene and the cyclization of (+)-citronellal under homogeneous (neat liquid) or heterogeneous (clay catalyst) conditions have been studied. In each case the dependence of reaction yield on time and the stereoisomer ratios of the products are unaffected by the heating mode.