Twelve cases of cutaneous mycosis fungoides (MF) with erythroderma, plaques and tumors were treated with photochemotherapy. Methoxsalen followed 2 h later by UV light (UVA) resulted in clinical clearing of skin lesions in 7 patients with plaque stage MF and 1 patient with erythrodermic MF. Four patients with plaque and tumor stage MF showed clearing of plaques but not tumors. Phototherapy units consisted of boxes with 16-64 UVA lights. The mean number 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/cm2. Histopathologic clearing of mycosis fungoides was demonstrated with clinical clearing.