The "polymerase chain reaction" (PCR) procedure for amplifying specific gene sequences has recently been combined with sequence-specific oligonucleotide (SSO) probe hybridization to develop a highly sensitive, rapid, and simple method for analyzing allelic variations in genomic DNA. In the present study we have used PCR/SSO to analyze partially purified DNA extracted from formalin-fixed, paraffin-embedded tissue specimens. We report that this DNA, including samples that were partially degraded, proved to be suitable for analysis by the PCR/SSO procedure.