Paclitaxel (PTX) is an essential anticancer drug used to treat breast cancer. Because it contains alcohol as a solvent, it is contraindicated in many Japanese breast cancer patients when they are suspected of alcohol intolerance. Aldehyde dehydrogenase 2 (ALDH2) is one of several enzymes that catalyzes dehydrogenation of aldehydes, and plays an important role in ethanol metabolism. Deficiency of this isozyme is believed to be responsible for facial flushing and other unpleasant symptoms following ethanol intake. In this study, we examined the safety of PTX for patients with the ALDH2 GA genotype.We performed ALDH2 genotyping on 25 patients with various cancers who were suspected to be intolerant to alcohol based on an interview using a simple question. Ten patients with the ALDH2 GA genotype, including 5 breast cancer patients, underwent chemotherapy containing PTX up to 100 mg/m2 (range 80-100 mg/m2), and were questioned about 16 alcohol-related symptoms at 11 timepoints to evaluate sensitivity to alcohol.All patients completed the first course of planned chemotherapy with either no or grade 1 alcohol-related symptoms.Our study suggests that PTX up to 100 mg/m2 can be used safely for patients with the ALDH2 GA genotype. To confirm the necessity of a genotyping test for ALDH2, further studies evaluating alcohol sensitivity in response to PTX among patients with the ALDH2 AA genotype are required.