OBJECTIVES:Nonbarrier modern contraceptive users often are less likely to use condoms, particularly with more intimate sex partners. We examine whether female sex workers (FSWs) in Swaziland who use nonbarrier contraception use condoms less consistently and whether this inverse association varies by relationship type. METHODS:In 2011, we conducted a survey among 325 Swazi FSWs using respondent-driven sampling. Each woman reported on condom use during sexual activity in the past month with up to 3 partner types (new clients, regular clients, noncommercial partners). We used a generalized estimating equation model to conduct a relationship-level multivariate logistic regression analysis of correlates of consistent condom use in the past month. We tested whether relationship type modified the effect of nonbarrier modern contraception on condom use. RESULTS:Each participant reported up to 3 observations, for a total of 892 measures of condom use in the past month. Compared with sexual activity with new clients, sex with regular clients and noncommercial partners was less likely to be protected by consistent condom use (adjusted odds ratio, 0.30 [95% confidence interval, 0.19-0.47] for regular clients; adjusted odds ratio, 0.15 [95% confidence interval, 0.09-0.24] for noncommercial partners). There was no significant association between condom use and nonbarrier modern contraceptive use. CONCLUSIONS:These data highlight the need to provide condoms and condom-compatible lubricants and targeted education programs for FSWs and their male sex partners to encourage the consistent use of these commodities with all sex partners, irrespective of the use of other contraceptive methods.