Head and neck squamous cell carcinomas (SCC) from 21 patients were analyzed for structurally rearranged or amplified proto-oncogenes by Southern blot hybridization. The int-2 proto-oncogene was amplified 3-5 fold in 5 (50%) of 10 laryngeal SCC and 2-3 fold in 5 (45%) of 11 nonlaryngeal SCC of the head and neck. Adjacent histologically normal tissue from the same patients had single int-2 gene copy number. Coamplification of int-2 and the epidermal growth factor receptor (c-erbB-1) gene was found in one laryngeal SCC and one SCC metastatic to the neck. No amplification or structural alterations of proto-oncogenes c-erbB-2/HER2, c-myc, H-ras-1, or K-ras-2 was detected in any of the head and neck tumors. In a survey of head and neck tumor-derived cell lines, int-2 was amplified 9 fold in a hypopharyngeal tumor cell line (FaDu), but not amplified in 3 laryngeal tumor cell lines. int-2 has been localized to the q13 band of chromosome 11. We used chromosome 11 specific probes to demonstrate that int-2 amplification was not due to complete or partial chromosome 11 duplication. int-2 amplification was localized to 11q13, but did not extend to the ets-1 locus 11q23. The results indicate that int-2 is frequently amplified in SCC of the head and neck and suggest that int-2 amplification may correlate with clinical disease progression.