A total of 130 human head and neck cancers was transplanted subcutaneously in athymic nude mice in order to obtain a series of xenografts. All tumours were derived from previously untreated patients. Initial growth, which was histopathologically confirmed, was observed in 34 cases (26.1%). Serial passages were successful in 12 of 23 cases (52.1%). Of 117 squamous cell carcinomas, 30 (25.9%) showed initial take in the mice. Poorly differentiated squamous cell carcinomas tend to grow more readily than moderately differentiated and well-differentiated ones. Material from metastatic lymph nodes tends to show a higher take than material from primary tumours. In general the tumour-volume doubling time decreased to 4-6 days when the number of passages increased. Histology of the xenografted tumours showed that transplantation had caused no major changes. No macro-, or microscopic signs of metastasis were observed in any of the mice. The implications of this model for fundamental and applied research are discussed.