Purpose: To evaluate the association between history of childhood sexual abuse (CSA) and having transactional sex among adolescents who have been in foster care. Methods: We used an existing dataset of youth transitioning out of foster care. Independent CSA variables included self report of history of sexual molestation and rape when participants were, on average, 17 years of age. Our outcome variables were self-report of having transactional sex ever and in the past year, when participants were an average age of 19 years. Separate multiple logistic regression analyses were conducted to assess the associations between CSA variables and transactional sex variables. Initial analyses were performed on both genders; exploratory analyses were then performed evaluating each gender separately. Total N = 732; 574 were included in the main analyses. Results: History of sexual molestation was significantly associated with increased odds of having transactional sex, both ever and in the past year (OR [95% CI]: 3.21 [1.26-8.18] and 4.07 [1.33, 12.52], respectively). History of rape was also significantly associated with increased odds of having had transactional sex ever and in the past year (ORs [95% CI]: 3.62 [1.38-9.52] and 3.78 [1.19, 12.01], respectively). Odds ratios in female-only analyses remained significant and were larger in magnitude compared with the main, non-stratified analyses; odds ratios in male-only analyses were non-significant and smaller in magnitude when compared with the main analyses. Conclusions: Both CSA variables were associated with increased likelihood of transactional sex. This association appears to vary by gender. Our results suggest that policymakers for youth in foster care should consider the unique needs of young women with histories of CSA when developing programs to support healthy relationships. Health care providers should also consider adapting screening and counseling practices to reflect the increased risk of transactional sex for female youth in foster care with a history of CSA. (Contains 2 tables.)