This research aimed to realize the spacial distribution of the infant mortality rates and of the proportion of low weight newborns in the southern area of Brazil and to test the association of those indicators with socioeconomic factors and health services. It is an ecological study put together from data collected from the 1,159 municipalities comprising the southern area of Brazil in the year 2000. The independent variables were the Municipal Human Development Rate, the illiteracy rate, the Gini coefficient, the proportion of poor people and people in homes with indoor plumbing and bathrooms, the annual average of medical visits for basic medical specialties, the monthly average of home visits per family and the number of medical clinics per 10,000 inhabitants. Kolmogorov-Smirnov, ANOVA and Kruskall-Wallis tests were performed and the Spearman coefficient of correlation was calculated. A significant statistical association was established between infant mortality and all the socioeconomic indicators. As for the proportion of low birth weight, it was associated with the proportion of people in homes with indoor plumbing and bathrooms, the annual average of medical visits for basic medical specialties, the Gini coefficient, poverty levels and monthly average of home visits per family. The spacial distribution of the diseases investigated allowed the identification of areas with the worst indicators investigated and which need greater government investment and attention. The public policies in infant health care should consider the need to improve the socioeconomic conditions and accessible health services in order to reduce the inequalities in health and the magnitude of the disease.