Social class differences in male mortality in New Zealand were investigated for each major disease grouping. The patterns found were similar to those for England and Wales with the lower social classes having mortality rates significantly higher than those of the upper social classes for each major cause of death. The strongest social class mortality gradients were found for deaths from accidents, poisonings and violence; diseases of the respiratory system; endocrine, nutritional and metabolic diseases; diseases of the genito-urinary system; and diseases of the digestive system. The gradients for coronary heart disease and neoplasms were weaker, but in the same direction as those found for other disease groupings.