From October 1981 to October 1985, 48 recurrent/persistent tumours (46 patients) were treated with a combination of interstitial hyperthermia and interstitial radiation therapy. All patients had failed other conventional treatment modalities. Radiation was administered using 192Ir with doses varying from 2000 to 6000 rad, depending on the dose of previous irradiation. Hyperthermia was administered with either localized current fields (LCF) or microwaves, two sessions each, minimum tumour temperature of 42.5 degrees C for 60 min. Of 37 lesions treated with at least one satisfactory hyperthermia session, there were 26 of 37 (70 per cent) complete responses and 11 of 37 (29.7 per cent) partial responses. Of 11 lesions with no sessions of satisfactory hyperthermia, there were no complete responses and only five partial responses. The detailed results are presented.