A total of 99 patients receiving adjuvant radiotherapy to the breast or chest wall were randomized to one of three washing policies: (1) not washing, (2) washing with water alone, and (3) washing with soap and water. Fifty-three of the patients were treated without the use of bolus, and 46 patients were treated using bolus for 10 to 15 of the 20 treatment fractions. Approximately half of the patients randomized to washing were tattooed. Subjective and objective measurements of acute skin reactions were found to be less in the two groups randomized to washing. There was little difference between the two washing groups. These findings were the same whether or not bolus was used. It is concluded that washing of the skin should be encouraged in patients undergoing radiotherapy associated with low skin doses.