Partial splenic embolization. An effective alternative to splenectomy for hypersplenism. Splenectomy for massive splenomegaly and hypersplenism carries a significant morbidity and mortality. We have used partial splenic embolization (PSE) as an effective alternative to splenectomy. Ten PSE procedures were performed on nine patients without mortality and with minimal morbidity. The age of the patients ranged from 8 months to 32 years (mean 14 years). The causes of splenomegaly and hypersplenism included cystic fibrosis with cirrhosis (2), tyrosinemia and cirrhosis (1); thalassemia (1), hemophilia with Human Immune Deficiency Virus infection (2), chronic hepatitis with portal hypertension (1), malignant histiocytosis (1), and Wiskott-Aldrich Syndrome (1). All procedures were performed under local anesthesia with sedation. A percutaneous femoral artery approach to the splenic artery was used to deliver Ivalon sponge particles (280-800 microns) into the spleen. Splenic infarction was assessed by postembolization angiograms. All of the patients except one demonstrated improvement of hematologic parameters. In one patient, however, cytopenia improved only after a second embolization. In the total series, there was an early mean rise of 8,600/mm3 in the leukocyte count (range 2,900-14,900) and 212,000/mm3 in the platelet count (range 30,000-718,000). Follow-up ranged from 4 months to 7 years. Improvement of the blood picture has been persistent in seven of the eight patients who showed initial improvement. Transient procedural complications included fever (5), pleural effusion (2), pneumonia (1), and splenic abscess (1). One patient had paralytic ileus lasting for 10 days and one patient developed a streptococcal peritonitis 3 weeks after embolization. No patient developed pancreatitis or vascular compromise of other abdominal viscera. 