Social class differences in cancer mortality among New Zealand men aged 15-64 years are examined for the period 1984-7. Age-standardised rates are presented for all cancer deaths, and for 23 specific cancer sites. The strongest social class mortality gradients were found for cancers of the larynx, liver, buccal cavity/pharynx, oesophagus, lung and for soft tissue sarcoma. On the other hand, rectal cancer, malignant melanoma, colon cancer, brain/nervous system cancers, and multiple myeloma showed higher death rates for the more advantaged socioeconomic groups. Lung cancer accounted for 54.1% of the overall social class gradient, and the major smoking related cancers (these include buccal/pharynx, oesophagus, larynx, lung and bladder, although it should be stressed that not all cases of these cancers are caused by smoking) accounted for 77.6% of the overall gradient.