A number of diabetic patients with diabetic neuropathy were treated with epalrestat, an aldose reductase inhibitor, since this drug was launched into the market in Japan. More than 5000 patients with diabetic neuropathy who were treated with epalrestat for 3-12 months were treated to analyze the efficacy and the adverse reactions of the drug in this study. The improvement rates of subjective symptoms (i.e., spontaneous pain, numbness, coldness, and hypoesthesia) was 75% (slightly improved or better) and those of nerve function tests (i.e., motor nerve conduction velocity, sensory nerve-conduction velocity, and vibration threshold) 36%. Adverse drug reactions were encountered in 129 cases (2.5%) out of 5249 patients, none of which were severe ones. Although data are limited, they strongly suggest that epalrestat is a highly effective and safe agent for the treatment of diabetic neuropathy.