A 58-year-old male who had a left hemicolectomy for descending colon cancer on July 1, 1993 was admitted to our hospital. A CT scan revealed a homogeneous low-density mass in the inferior portion of the spleen. Under the diagnosis of solitary splenic metastasis, a splenectomy was performed on August 10, 1995. Histologically, splenic tumor revealed moderately differentiated adenocarcinoma consistent with the primary tumor. Flow cytometric analysis revealed DNA diploidy in the primary tumor, and DNA aneuploidy (DNA index = 1.76) in the metastatic tumor. Using fluorescence in situ hybridization with p17 H8, numerical aerrations of chromosome 17 were observed in the primary tumor.