As part of the Combatting Childhood Communicable Diseases (CCCD) project funded by the US Agency for International Development (USAID), the Zairian CCCD programme conducted surveys in the rural health zones of Kingandu and Pai-Kongila, Zaire, in 1984-1985 and 1988-1989 to determine whether a strategy of selective primary health care would affect childhood mortality. This paper describes the changes in the medical care infrastructure and the increasing coverage of selected services. The strategies evaluated were vaccination, oral rehydration therapy, and treatment of febrile episodes with antimalarial drugs for children; and tetanus vaccination and malaria prophylaxis for pregnant women. The health infrastructure in the Kingandu and Pai-Kongila Health Zones expanded considerably from 1984 to 1989, with health centres increasing from 7 to 18. During this period, economic conditions deteriorated moderately, with the nation experiencing nearly 700% inflation. Medical care costs remained stable because of external subsidies. Use of health services was assessed in 1984, 1988, and 1989. Between 1984 and 1989, the proportion of children aged 12-23 months vaccinated against measles increased from 22% to 71%. Coverage with other vaccine antigens increased similarly. Women's knowledge of the correct recipe for the preparation of sugar-salt solution increased from 0% to 61%. Reported treatment at home with sugar-salt or oral rehydration solution increased from 6% to 53%. The proportion of children with febrile episodes who were treated presumptively for malaria with chloroquine remained unchanged (47% in 1984; 44% in 1988). We conclude that, despite a moderate deterioration in economic conditions, Kingandu and Pai-Kongila Health Zones achieved remarkable increases in use of selected health services between 1984 and 1989, especially in vaccination coverage.