11 edentulous patients (mean age 71.2 years) with oral or oropharyngeal malignancies were examined clinical and microbiologically before, during, and after receiving tumoricidal radiation doses (26.4-74 Gy) towards the head and neck regions. The effect of a supervised oral hygiene program and a saliva substitute (Va-OraLube) was studied. The 9 patients who survived the observation period, showed increased xerostomia and mucositis related to increased radiation. Radionecrosis or oral infections were not observed. The patients wore their dentures throughout the observation period and preferred to use the saliva substitute. The initial number of acidophilic bacteria was high, Candida albicans were present in low numbers and enteric bacteria occurred more frequently than normally. There was a reduction of micro-organisms after introduction of the hygiene program. It is concluded that careful planning of the radiotherapy, pre-radiation oral examination, denture control and instruction and an effective oral hygiene program are essential for the reduction of oral complications in edentulous patients receiving tumoricidal radiotherapy to the head and neck regions.