Paclitaxel is mainly eliminated by CYP2C8 in the liver. CYP2C8 is strongly inhibited by the clopidogrel metabolite acyl-β-D-glucuronide. To determine if this interaction has clinical relevance, we identified 48 patients treated with clopidogrel and paclitaxel using databases and a prescription register. Peripheral sensory neuropathy was retrospectively evaluated from medical charts and compared to that of 88 age and sex matched controls treated with paclitaxel and low dose aspirin. By a cumulative dose of 1500 mg paclitaxel, 35% of the patients had developed severe neuropathy. The overall hazard ratio between clopidogrel use and severe paclitaxel neuropathy was 1.7 (95% CI, 0.9-3.0). Among those receiving a high dose paclitaxel regimen, the hazard ratio was 2.3 (95% CI, 1.1-4.5). Our study indicates that clopidogrel is associated with a clinically relevant increased risk of neuropathy in patients treated with high dose paclitaxel. This article is protected by copyright. All rights reserved.