The growth of Protestantism in Brazil has been associated with changes in mortality and health-related outcomes. Recent research has suggested that affiliation with Protestant churches may positively influence their members' well being by: 1) providing moral directives, 2) creating formal or informal sanctions, and 3) promoting social networks and support. This article uses data from the 1996 and 2006 Brazilian Demographic Health Surveys (DHS) and Cox's proportional hazard models to examine the relationship between infant mortality and mothers' religious involvement. Unadjusted results show that differences in the hazard ratios of infant mortality by mothers' religious involvement are considerable and statistically significant. When one controls demographic and socioeconomic variables in the 1996 DHS, the baseline relationship disappears, supporting the hypothesis of selectivity. Results using the 2006 DHS are somewhat different and suggest that the association between religious involvement and infant mortality was stronger in Brazil in 2006 than in 1996. This research should encourage future studies on religious involvement and health-related outcomes in Brazil. This topic deserves further consideration from Brazilian demographers not simply because this country has undergone enormous changes in its religious landscape over recent decades, but also because religion can affect believers' lifestyles and behaviors, and this can indirectly influence their health and well-being.