All deaths of children under one year of age and residing in the Pau da Lima Health District, in the city of Salvador, Bahia, Brazil, during the year 1991 were investigated through home visits and analysis of patient files. The study measured effectiveness of health services by verifying potentially avoidable deaths and the level of medical care these children received. More than half of the total of 47 deaths were related to causes considered amenable to prompt action by health services; 10 (21.3%) of the deaths occurred at home or in public (outside of health care facilities). Loss of information occurred in 36 (76.6%) of the mother's interviews, related to incomplete information on the death certificate and to changes of address. Analysis of patient files in the health clinics showed a 58.3% loss of information, indicating low-quality organization of hospital statistics; there was a prevalence of consultations classified as inadequate or barely adequate, due mainly to problems with physical examination and treatment. Despite this study's operational limitations, the results point to problems of access, effectiveness, and adequacy in the health care process.