PURPOSE: To evaluate the radiologic findings of direct invasion of the spleen by malignant tumors of adjacent organs. MATERIALS AND METHODS: We retrospectively reviewed the CT(n=6) and MR(n=3) images of six patients with direct invasion of the spleen by malignant tumor of left lower lung, stomach, colon, pancreas, left kidney, and left adrenal gland. We evaluated the tumor margin, attenuation or intensity, perisplenic fat infiltration, regional lymphnode enlargement, and invaded site of the spleen. RESULTS: Ill-defined masses were found in the spleen with central necrosis and infiltration into perisplenic fatty tissue in all six patients; left adrenal mass was present also in three patients. Regional lymphnode enlargement was found in four patients. The masses showed heterogenous low attenuation on CT. The invaded site was variable and corresponding to their anatomical connections to the spleen. CONCLUSION: Direct invasion of the spleen by malignant tumors of adjacent organs showed ill-defined masses with central necrosis and were commonly associated with infiltration to perisplenic fatty tissue and adrenal invasion. The pattern and invaded site can be helpful to assess the primary cancer.