BACKGROUND The hazards of acute radiation exposure are well known. Bone marrow failure from total body gamma or neutron irradiation is the most clinically relevant aspect of acute radiation disease. With nonhomogeneous exposure, as is characteristic in accidents, other organ systems, such as the skin, may be more important in determining clinical prognosis. This became obvious in the two worst radiation accidents since 1945, the Chernobyl accident in April 1986 and the Goiania accident in September 1987. OBJECTIVE Our purpose was to describe the characteristic chronic sequelae of accidental cutaneous radiation in a group of patients who survived the Chernobyl nuclear power plant accident. METHODS Fifteen patients with the delayed type of the cutaneous radiation syndrome were examined between September 1991 and January 1992. All patients had a history of acute radiation disease. The exposure pattern was characterized by partial body exposure with high doses of beta and gamma irradiation from radioactive water, steam, or dust. RESULTS Radiation-induced lesions were confined primarily to the legs and distal arms, but sometimes involved up to 50% of the total body surface. In addition to telangiectases, radiation keratoses, and radiation ulcers, hemangiomas, hematolymphangiomas, splinter hemorrhages in the distal nail bed, lentiginous hyperpigmentation, and severe subcutaneous fibrosis were noted. No malignant transformation could be detected. Associated diseases included cataracts, chronic hepatitis, and recalcitrant bacterial and herpesvirus infections. CONCLUSIONS After accidental partial body exposure to high doses of beta and gamma irradiation, the predominant involvement of the skin, described as the cutaneous radiation syndrome, can become the characteristic feature. This causes longlasting, serious diagnostic and therapeutic problems.