Brazil has a high prevalence of tubal ligation. The hypothesis that it indicates undercover birth control efforts specifically addressed to the poorest sector of Brazilian society has been raised. The purpose of this paper is to evaluate whether there are differences in rates of tubal ligation depending on socioeconomic status. Data were gathered from interviews with 1335 women 15-49 years of age, of low or lower-middle socioeconomic status, carried out in 1991 in two regions of the State of São Paulo. The results showed an apparently higher prevalence of tubal ligation among women with less schooling,, but also among those living in better housing. However, after controlling for women's age, these associations disappeared, suggesting that they were explained by lower educational levels and greater economic resources of women of older age, where the latter factor is more heavily associated with a higher prevalence of tubal ligation. The complexity of the associations between socioeconomic status and tubal ligation are discussed, including the correlations between socioeconomic status and C-sections, which are in turn closely related to tubal ligation.