Between 1980 and 1991 the proportion of Zambian children dying before reaching five years of age rose from 15 to 19 percent. This paper explores why this happened. There are no data on trends in morbidity. However, there is information about the number of visits to health facilities each year by children with common illnesses. They increased for malaria but fell for diarrhoea and acute respiratory infection. This does not suggest a dramatic increase in the incidence of these illnesses. There also was no evidence of an increase in malnutrition. The HIV epidemic began to affect health by the end of the decade, but it does not fully explain the large increase in childhood mortality. Government health expenditure fell substantially, in real terms, during the 1980s. There was a particularly sharp fall in non-personnel expenditure on rural health services. This appears to have had a negative impact on the effectiveness of primary health care. Zambian mothers were as likely as mothers elsewhere in Sub-Saharan Africa to consult a health worker when their child fell ill, but their child was less likely to receive specific drug therapy. One sign that health services had deteriorated was that case fatality rates rose in health facilities.