A method for typing microsatellite polymorphisms is described. It involves amplification using the polymerase chain reaction with one primer 5' end-labeled with 32P. Alleles are separated by denaturing gel electrophoresis and detected by autoradiography. Standardized conditions allow accurate typing of almost all microsatellite polymorphisms, and results are usually obtained within 24 h. © 1993 Academic Press, Inc.