Radioactively labeled polymerase chain reaction (PCR) products are being used in an increasing number of molecular biology research techniques. Among these are PCR-based polymorphism assays, such as linkage analysis (1 ) and detecting allelic loss in cancer cells (2 ). Other uses of radioactive PCR include generating probes for Southern and Northern blotting (3 ) and screening for polymorphisms and point mutations by the single-strand conformation polymorphism (SSCP) technique (4 ).