We examined echograms of 44,634 spleens produced over a period of 10 years (1977-1987). The rate of appearance of focal lesion in the spleen was 0.13% (57/44,634). Twenty-two cysts, 8 abscesses, 16 metastatic tumors, 2 hematomas, and 2 infarctions in 57 cases were diagnosed by autopsy, operation, echography, angiography, X-CT and/or clinical examination. Seven other cases could not be definitively diagnosed. Characteristic echo images of true cysts included thin wall and anechoic images, while false cysts produced thick capsule images and internal echoes. Abscesses usually formed in hematological disorders in immunocompromised hosts. We were generally able to diagnose abscesses without multiple small nodules. These are the metastases of malignant lymphomas and/or abscesses. Metastatic lesions from carcinomas of the stomach, rectum, and esophagus displayed characteristic patterns of high internal echo with a central anechoic area. Ultrasonic examination was effective in diagnosing focal lesions in the spleen. In several cases, however, an accurate diagnosis would have to include other clinical findings.