The clinicopathologic features of nine cases of peripheral T-cell lymphoma were analyzed. Although the youngest patient was 18 years old, the median age was 59.8 years. They usually presented with widespread disease and had an aggressive course. Seven have died with a median survival of 10.9 months. Five cases were of mixed cell type, sharing certain histopathologic features that we believe are characteristic of peripheral T-cell lymphomas. Three cases were of large cell type; one was a small cell (PDL) type. This latter patient lived symptom-free without treatment for over 3 years, despite stage III disease. Another patient, whose tumor had nodular sclerosis-like fibrosis, is in complete remission two years after chemotherapy for stage III B disease. Because peripheral T-cell lymphoma is morphologically heterogeneous, it may be clinically heterogeneous as well. We believe that classification according to a modified Rappaport system may clarify possible variations in biologic behavior.