The diagnosis of malignant lymphoma based on cytologic preparations is a source of much debate. The purpose of this study was to assess the ability of a number of pathologists to diagnose and classify lymphoma using cytospin preparations, and to compare the rate of agreement between cytopathologists and hematopathologists. One hundred twenty-five cytospins prepared from histologically confirmed hematologic lesions were examined retrospectively and independently by four hematopathologists/fellows and two cytopathologists without knowledge of the final diagnosis; the results were compared with the final diagnoses derived from histology and immunophenotyping. Eighty-one cases were histologically diagnosed as lymphoma (including 67 cases of B-cell non-Hodgkin's lymphoma), and 44 cases represented a reactive process histologically. The distinction of a malignant from a benign process was made in 75% of the cases by cytospin examination, with cytopathologists correctly diagnosing 75% and hematopathologists 76% of the cases. The accuracy rate for subclassification of the lymphoma cases was 49% (46% for cytopathologists, 52% for hematopathologists). The cytopathologists correctly recognized large-cell lymphoma at an increased frequency compared with the hematopathologists (70% vs. 56%, P = 0.11), while the hematopathologists showed a greater ability to recognize and classify nonfollicle center low-grade B-cell lymphomas (57% vs. 28%, P = 0.01). We conclude that cytopathologists and hematopathologists generally achieve similar accuracy rates in the morphologic evaluation of cytologic preparations of lymphoid lesions, though some differences in their performance do exist.