Twelve cases of cutaneous mycosis fungoides (MF) with erythroderma, plaques, and tumors were treated with photochemotherapy. Methoxsalen followed two hours later by ultraviolet light (UVA) resulted in clinical clearing of skin lesions in seven patients with plaque stage MF and one patient with erythrodermic MF. Four patients with both plaque and tumor stage MF showed clearing of plaques but not the tumors. Phototherapy units consisted of boxes with 16 to 64 UVA lights. The mean numbers of treatments to clear was 17.4. The mean total dose to clear was 134.8 joules. The mean dose of maintenance UVA was 5.6 joules/sq cm. Histopathologic clearing of mycosis fungoides was demonstrated with the clinical clearing.