Background: Relatively little is known about the frequency and factors associated with miscarriage among women living with HIV. Objective: The objective of the study was to evaluate factors associated with miscarriage among women enrolled in the Women's Interagency HIV Study. Study Design: We conducted an analysis of longitudinal data collected from Oct. 1, 1994, to Sept. 30, 2017. Women who attended at least 2 Women's Interagency HIV Study visits and reported pregnancy during follow-up were included. Miscarriage was defined as spontaneous loss of pregnancy before 20 weeks of gestation based on self-report assessed at biannual visits. We modeled the association between demographic, behavioral, and clinical covariates and miscarriage (vs live birth) for women overall and stratified by HIV status using mixed-model logistic regression. Results: Similar proportions of women living with and without HIV experienced miscarriage (37% and 39%, respectively, P =.638). In adjusted analyses, smoking tobacco (adjusted odds ratio, 2.0), alcohol use (adjusted odds ratio, 4.0), and marijuana use (adjusted odds ratio, 2.0) were associated with miscarriage. Among women living with HIV, low HIV viral load (<4 log10 copies/mL) (adjusted odds ratio, 0.5) and protease inhibitor (adjusted odds ratio, 0.4) vs the nonuse of combination antiretroviral therapy use were protective against miscarriage. Conclusion: We did not find an increased odds of miscarriage among women living with HIV compared with uninfected women; however, poorly controlled HIV infection was associated with increased miscarriage risk. Higher miscarriage risk among women exposed to tobacco, alcohol, and marijuana highlight potentially modifiable behaviors. Given previous concern about antiretroviral therapy and adverse pregnancy outcomes, the novel protective association between protease inhibitors compared with non–combination antiretroviral therapy and miscarriage in this study is reassuring.