Prostatic cancer in 1885 autopsy cases was classified according to the number of organs involved in metastasis, and a comparison was made concerning the frequency of metastasis to the various organs. The frequencies of metastasis to the lungs and para-aortic lymph nodes were low in cases with single-organ involvement (4.6% and 2.3%, respectively), but increased rectilinearly in accordance with the number of organs involved and became high in cases with metastasis to three or more organs (49.1% and 21.8% in total, respectively). On the other hand, the frequencies of local extension to the bladder and invasion of the pelvic lymph nodes were high even in cases with single-organ involvement (34.5% and 9.2%, respectively) and were not significantly changed regardless of the number of organs involved. No significant correlation was seen between pelvic and para-aortic lymph node involvement. In cases with single-organ involvement, metastasis to the lumbar spine occurred frequently, but those to the ribs, sternum, and ilium occurred less frequently. There may be multiple metastases in cases with metastases to the para-aortic lymph nodes, sternum, and ilium. The number of metastatically involved organs is useful in analyzing the mode of metastasis.