The case of a 49-year-old Negro man is described in whom sarcoidosis was followed by mycosis fungoides and a fatal lymphoma of mixed cell type. A review of the literature revealed 14 previously reported cases in which sarcoidosis and a malignant lymphoreticular disease were associated in the same individual. Of these, however, only one appears to have had both diagnoses adequately documented. In the present study, Kveim tests were performed on 21 additional patients with proved lymphoreticular malignancies of various types. Only one of these patients produced a positive reaction. As this patient had little other evidence of systemic sarcoidosis, the Kveim test in this instance may represent a false-positive reaction. The possibility of a relationship between sarcoidosis and the malignant lymphoreticuloses is discussed.