Coronary heart disease mortality has shown a downward trend in New Zealand during the 1970s as in most western countries. In contrast, Sweden, which has a similar health care system to New Zealand, has shown a continuing increase in coronary mortality for males during the same period. Medical and surgical management of ischaemic heart disease in Sweden is very similar to that found in New Zealand and possibly more intensive in some respects. Hypertension detection and control measures have been successfully applied in Sweden as in New Zealand and a similar reduction in cigarette smoking has occurred in both countries. However, whereas significant beneficial changes have occurred in the New Zealand diet during the past two decades, dietary change, although actively promoted, has not occurred in Sweden for various reasons. The lack of dietary change in Sweden has been coupled with a probable reduction in habitual physical activity in the adult population. Diet appears to be a principal determinant of coronary disease incidence, and population dietary change an important prerequisite for effective primary prevention. In the absence of dietary change, the effect of primary and secondary preventive measures may be limited. The reasons that appropriate dietary recommendations have not been successful in Sweden can be examined and are instructive for effective prevention in all countries.