This study analyzed a series of 140 consecutive fine needle aspiration biopsies of the spleen (sFNAB) collected over a period of nine years. sFNABs were performed by the authors using a 22-gauge spinal needle, and 23-gauge needle in pediatric patients, with a subdiaphragmatic approach. Ultrasound assistance was utilized in 35 cases. Four of the cytocentrifuge specimens were also prepared with part of the aspirated material and used for immunocytochemical staining. Study of these biopsy specimens revealed various benign conditions, such as white pulp hyperplasia, myeloid metaplasia, storage disease, and granulomatous processes and abscesses. Malignant neoplasms were represented by non-Hodgkin's and Hodgkin's lymphomas, leukemias, malignant histiocytoses and metastases. sFNAB was the only diagnostic procedure employed for the morphologic assessment of 60 benign and of 2 malignant cases. In all the other cases sFNAB gave the first diagnosis that was confirmed on surgical specimens. In 2 cases splenic bleeding occurred; one of them required splenectomy. Diagnostic and technical problems are discussed. The authors consider sFNAB a useful procedure, especially in the study of hematologic disorders and in all cases in which splenomegaly is not related or correlated with any clinical finding.