The mutations of the p53 tumor suppressor gene is one of the most common genetic abnormalities in human cancers. To establish the laboratory procedures for the detection of p53 mutation, we employed PCR-SSCP(polymerase chain reaction-signle strand conformation polymorphism) and direct sequencing methods. PCRs were performed for the highly conserved regions of p53 gene with 4 sets of 32P-labelled primers, encompassing exon 4, exons 5 and 6, exon 7, and exons 8 and 9. SSCP analysis was performed with polyacrylamide gel containing 5% glycerol at room temperature or gel without glycerol. Preliminarily nine head and neck cancer tissues from 8 patients were analyzed. Two samples showed mobility shifts in SSCP analysis for exons 5 and 6. Mobility shifts were further characterized with direct sequencing of allelespecific PCR products. One was G to A transition of the third base of codon 146 resulting in TGG(tryptophan) to TGA nonsense mutation. And the other was G to T transversion of the second base of codon 154 resulting in GGC(glycine) to GTC(valine) missense mutation.