Visceral involvement is a relatively common but poorly appreciated occurrence in patients with mycosis fungoides. The lungs are the most common site of visceral involvement. Here we present two cases of mycosis fungoides with pulmonary parenchymal involvement, one of them proven by biopsy. Both patients were treated with whole-lung radiation therapy, with complete disappearance of the lesions and improvement of respiratory symptoms. There was no significant radiation-induced pulmonary toxicity. One patient continues to be alive with no recurrence in the lungs 17 months after radiation therapy.