Research has identified sexual concurrency as a potential underlying driver of high HIV infection levels in sub-Saharan Africa, though few studies have explicitly examined the contribution of marital concurrency. Utilizing a multi-level model of Demographic and Health Surveys with HIV-biomarkers for sixteen African countries, this study assessed the relationship between an individual's HIV serostatus and rates of formal and informal marital concurrency (% polygamous unions, % extramarital partner past year) among married men and women. Mutually exclusive regional-level variables were constructed and modeled to test the contextual risk posed by living in a region with higher levels of formal and informal marital concurrency controlling for individual sexual partnerships and other covariates. Compared with regions where monogamous unions were more prevalent, the odds of having HIV were higher among individuals living in regions with more informal marital concurrency, but lower in regions with more polygamy, even accounting for individual-level sexual behavior. These results can help inform prevention policy and practice in sub-Saharan Africa.