To assess the value of fine needle aspiration cytology (FNAC) in the diagnosis of non-Hodgkin's lymphomas (NHL), we retrospectively studied all the cases diagnosed cytologically as NHL in our laboratory during a five-year period (1987-1991). We also traced cases in which FNAC failed to diagnose NHL and where the diagnosis was made subsequently by histopathology. Fine needle aspiration (FNA) was performed on both peripheral/palpable and deeply situated lesions. A total of 164 specimens were studied cytologically, and for 130 of them a histologic report was available. In 83 of the cases, FNA was carried out as part of the initial evaluation, and in 81 the diagnosis of NHL was known and FNA was performed to confirm or exclude a relapse. In 76 cases for which morphology was inconclusive the immunophenotype was assessed by immunocytochemistry. There were three false-negative and one false-positive result; in none of them was immunophenotyping performed. No discrepancy was observed in the distinction between low and high grade lymphomas, but this was feasible in only 115 of the 164 specimens studied. We conclude that the method is a feasible, rapid and inexpensive first approach in the evaluation of patients with NHL. FNAC may be substituted for histology in the occasional patient for whom the surgical risk outweighs the inaccuracies of the procedure.