The lung function of 79 Maori workers was compared with that of 31 workers from Western Samoa and with 616 Europeans from the same factory. No significant difference was found in either forced expiratory volume in one second (FEV1) or in forced vital capacity (FVC) between the two Polynesian groups. The combined 110 Polynesians had a lung function which was significantly lower, by about 9%, than that of the Europeans working in the same factory. The lung function differences did not appear to be related to smoking, occupational or environmental factors. While it seems likely that the cause of the differences is a major gene effect a non-job-related social factor cannot yet be completely excluded. Charts for predicting FEV1 and FVC in male Maori and Samoan workers in New Zealand are given.