A 50 year old man with actinic reticuloid developed a diffuse malignant lymphoma 7 years after the beginning of the dermatosis. Biopsy of lymph node showed a polymorphic proliferation with lymphocytes, numerous reticular cells and several Sternberg-like cells. An ultrastructural study showed an indifferentiate lymphocyte proliferation and numerous malignant reticular cells without the Sternberg cell picture. In this patient we discuss the role of immunosuppressive therapy, chronic herpes virus infection and chronic antigenic photostimulation. Up to now, this is the third case of an association between actinic reticuloid and malignant lymphoma.