A controlled trial of 4-weeks oral photochemotherapy (PUVA) on 14 patients with severe symptomatic dermatographism produced a clinically useful reduction in itching in five patients. In four of these patients itching had relapsed to pre-treatment levels within 3 months of finishing the PUVA course. A comparison of the weal and flare responses on exposed and covered (control) skin using a calibrated dermographometer showed no significant change in skin reactivity, even in the patients who experienced symptomatic relief. While PUVA may temporarily reduce itching in some patients with symptomatic dermographism, its use cannot generally be justified for treating this type of physical urticaria.