Alcoholic cerebellar degeneration (ACD) is a pivotal neurological complication in alcoholics. However, although there are a few autopsy reports and some data on its frequency, it is considered very rare in Japan. The aims of this study were (1) to estimate the frequency of the disease in Japanese autopsy cases, and (2) to examine the clinicopathological features of symptomatic and asymptomatic cases of ACD. We reviewed the records of 1,509 Japanese autopsies obtained from three autopsy series in Japan, and selected all 55 cases (3.6%) with alcoholism. On neuropathological reexamination, ACD was confirmed in six male alcoholics [0.4% of all subjects; 10.9% of all alcoholics; mean age at death 59.3+/-13.4 years (+/- SD)], including three asymptomatic cases. These frequencies were much lower than some previous Western findings, but more common than that has been expected in Japan. The frequencies of memory impairment and ataxia in ACD cases were significantly higher than those in alcoholics without any alcohol-related pathologies. In ACD cases, loss of Purkinje cells, narrowing of the width of the molecular layer, and tissue rarefaction in the granular layer were observed in the anterior and superior portions of the vermis of the cerebellum. In adjacent regions, the Purkinje cell and molecular layers were more mildly affected. The distribution of severely affected regions was more restricted in the asymptomatic cases than in the symptomatic cases. This study confirmed the frequency of asymptomatic cerebellar degeneration in alcoholics, suggesting that early intervention in alcoholism in the subclinical phase is important to prevent the development of cerebellar symptoms.