Although loss of heterozygosity (LOH) on the p53 locus is frequent in squamous cell carcinomas of the head and neck (SCCHN), controversy still remains regarding the prognostic significance of such an event. Eighty consecutive SCCHN were studied. DNA was extracted from matched sets of normal and tumour tissue and used for polymerase chain reaction amplification of microsatellite markers located in the p53 locus. LOH at the p53 locus was found in 39 (70%) of the 56 informative cases. No relationship was found between p53 LOH and age, site, T stage, N stage, disease stage, and histological differentiation. Recurrence occurred in 53% of the cases with LOH and in 58% of the cases without it (P = 0.28). Moreover, no statistically significant association was found between p53 LOH and disease-specific survival (log-rank P = 0.98). These data suggest that although LOH at the p53 locus is common in SCCHN, this finding is of little clinical significance.