Describes results for a nonconventional method to cure malignant tumours using microwaves with non-thermal power levels. A number of 25 rats were grafted with cancerigenic cells. 10 from these animals were kept as controls and 15 were irradiated with microwaves in 7.5 GHz-10.5 GHz frequency range and non-thermal power levels densities (less than 5 mW/cm2). A total and definitive tumoral remission was ascertained for 12 irradiated rats; for 2 experimental animals there was a tumoral recurrence and they died. All control animals died, maximum survival time being 34 days.