Background: Social support resources are thought to buffer stressful life events and have been associated with numerous health outcomes in industrialized countries. Because the nature of supportive relationships varies by culture and social class, we studied the relationship of informal social support and networks to self-rated health among low-income women in northeastern Brazil. Methods: Participants included 595 randomly sampled mothers from nine low-income communities in Teresina, Piauí, Brazil. Data on sociodemographic variables, social support, quality of the partner relationship, and selfrated health were collected cross-sectionally in 2002. Using multivariable logistic regression, we modeled the association between different aspects of social support and self-rated health. Results: Poor or fair health was reported by 47% of participants. Women with poor partner relationships had an increased likelihood of poor or fair health (OR 1.7, 95% CI 1.1-2.7), as did those with no material support for food or money (OR 1.6, 95% CI 1.2, 2.0) and no support to resolve a conflict (OR 1.5, 95% CI 1.1, 2.1). Likewise, women with the lowest scores of the Medical Outcomes Study (MOS) social support survey were more likely than other women to report poor or fair health (OR 1.5, 95% CI 1.0, 2.1).Conclusions: Poor quality of a partner relationship, lack of support to resolve a conflict, and lack of material support as well as such sociodemographic variables as low education, poor sanitation, and depressive symptomatology are associated with lower health status in a population of low-income women from northeastern Brazil.