Human carboxyl ester lipase (CEL) secreted by the pancreas into the duodenum is a glycoprotein playing an essential role in the intestinal processing of cholesterol and lipid-soluble vitamins. The gene encoding CEL was known to contain a tandemly repeated sequence of the 11-amino-acid motif in the C-terminal region. We characterized its polymorphic features and found that there are five different alleles in Japanese populations and six in Caucasians. The allele containing 16 repeats is the most common in both populations. Although the distribution of the alleles seemed to be different in the two populations, the difference was not statistically significant. This polymorphism may influence the function of this enzyme and be a useful genetic marker to study diseases associated with cholesterol absorption.