Background: We have observed, in patients undergoing high-dose PUVA treatment, a type of keratosis not previously described. The lesions usually occur on the sides of the palms or soles and are clinically distinct. They are generally painless and often go unnoticed by patients. Objective: We sought to further characterize these lesions both clinically and histologically. Methods: Patients attending a PUVA clinic were screened for these keratoses. Other PUVA-related complications were recorded. Representative lesions were photographed, and biopsy specimens were taken. Results: Biopsy specimens were taken from lesions in 10 patients. All had plaque psoriasis and had received high UVA doses (>1000 J/cm²) through PUVA therapy. All patients had PUVA-induced keratoses elsewhere, but the number varied greatly between patients. The hand and foot keratoses were well defined and circular and had a characteristic histologic appearance, with a sharp demarcation between normal and abnormal markedly pale–staining epidermis. Conclusion: These lesions are a further cutaneous manifestation of prolonged PUVA therapy. (J Am Acad Dermatol 2000;42:476-9.)