Cetylpyridinium chloride (CPC) has been found to be effective in reducing microbial contamination in apples. A sensitive and specific HPLC method was developed to determine CPC residues in apples treated with CPC. This method involves ion exchange solid-phase extraction, and the use of stearylpyridinium chloride (SPC) as internal standard. Limit of quantitation, was 0.5 microg/ml of CPC for the apple ethanolic extracts. The observed residues in apple (2.35-4.35 microg/g of apple) were lower than those previously reported for chicken and beef. The method is specific, sensitive, reproducible and accurate.