Twenty-four patients with chronic symmetrical constitutional eczema of the hands treated with a combination of topical therapy and conventional superficial X-ray therapy. In a double-blind fashion one hand was irradiated with 100 rad (1Gy) at 50 kV on three occasions at intervals of 21 days and the other hand was given a placebo treatment. Each hand received the same topical medication, which was adjusted as necessary at each visit. The patients were seen 6, 9 and 18 weeks after X-ray therapy commenced. A significantly better therapeutic result, as assessed independently by both the patient and the observer, was recorded on the hand which had received active X-ray treatment. The advantage bestowed by active X-ray therapy was greatest 6 to 9 weeks after the start of treatment, but was still present after 18 weeks.