Ultrasonically (US) guided percutaneous tissue core biopsy of the spleen was done on 46 patients with malignant lymphomas. The biopsies were undertaken as a staging procedure in 32 patients, as a restaging procedure in 7, during follow-up in 2, and as a diagnostic step in 5 (previously undiagnosed cases with clinically and ultrasonographically suspected lymphoma). In 45 patients, the tissue core specimens obtained by US-guided biopsies were sufficient for a correct histologic examination; in one patient, the specimen was considered inadequate. The tissue core specimens showed splenic involvement in 12 patients and normal splenic tissue in the other 33. These latter cases were confirmed by splenectomy, by laparoscopy with larger splenic biopsy needles, and by clinical and US follow-up over a period of 6 to 30 months. In all previously undiagnosed patients (five), splenic biopsies allowed histologic subtyping. Additional immunologic subclassification into B-cell and T-cell types of lymphomas was done in two instances. There were no complications in this series. These results suggest that percutaneous US-guided splenic tissue core biopsy is a useful and safe technique for the diagnosis, staging, and follow-up of malignant lymphoma.