Recent research has highlighted the risk of HIV infection for married teenage women compared with their unmarried counterparts (Clark, 2004). This study assesses whether a relationship exists, for women who have completed their adolescence (age 20–29 years), between HIV status with age at first marriage and the length of time between first sex and first marriage. Multivariate analysis utilizing the nationally representative 2004 Cameroon Demographic and Health Survey shows that late-marrying women and those with a longer period of pre-marital sex have the highest risk of HIV. Although women in urban areas overall marry later than their rural counterparts, the positive relationship between age at marriage and HIV risk is stronger in rural areas. The higher wealth status and greater number of lifetime sexual partners of late-marrying women contribute to their higher HIV risk. Given that the age at first marriage and the gap between first marriage and first sex have increased in recent years, focusing preventive efforts on late-marrying women will be of much importance in reducing HIV prevalence among females.