We have examined 48 squamous cell cancers of the larynx for loss of heterozygosity (LOH) and microsatellite instability at chromosome 9p near the p16 tumour suppressor locus, at chromosome 17p at the p53 tumour suppressor locus, and at 17p at another microsatellite locus (D17S520). In p53 LOH was higher (33-45%) than in D17S520 (21%). Near the p16 locus LOH varied from 28-38%. Replication errors were found from at least one locus in 23% of the patients. These data suggest that p53 is an important gene in laryngeal cancer while loci around p16 appear less likely candidates.