Primary health care (PHC) services have been advocated as a means by which less developed countries may improve the health of their populations even in the face of poverty, low levels of literacy, poor nutrition and other factors that negatively influence health status. Using aggregated data from the World Bank and UNICEF this study examined which factors, both within the health care system and outside of it, are associated with under-5 mortality rates in 22 countries of Latin America and the Caribbean during the 1990s. In a multivariate analysis using generalized estimating equations for repeated measures, five factors were found to be independent predictors of lower under-5 mortality rates (U5MRs). These were vaccination levels, female literacy, the use of oral rehydration therapy, access to safe water and GNP per capita. When the magnitude of these associations were assessed, higher levels of GNP per capita was found to be very weakly associated with lower U5MRs, compared with female literacy and vaccination rates. These findings suggest that government policies which focus only on promoting economic growth, while not making important investments in PHC services, female education and access to safe water are unlikely to see large improvements in health status.