BACKGROUND: Kenya has the fourth-largest HIV epidemic across the globe. Disclosure of HIV-positive status plays a critical role in the prevention of HIV transmission. Disclosure, specifically to sexual partners, has been shown to foster safer sexual behaviors in addition to emotional, social, or monetary support from partners. OBJECTIVE: This study was conducted to identify factors associated with HIV-positive status disclosure to sexual partners compared to disclosure to other than sexual partners. METHODS: A cross-sectional study was conducted from May to August 2012 among 497 HIV-positive women 19-49 years of age who had sex in the past six months. Participants were recruited from the Kenyatta National Hospital and Mbagathi Direct Hospital in Nairobi, Kenya. A questionnaire was administered to obtain data on HIV disclosure. Bivariate and multivariable logistic regression analyses were conducted to identify factors associated with disclosure of HIV-positive status to sexual partners. RESULTS: Of the 497 women, 349 reported to whom they had disclosed their HIV status. Approximately 34% had disclosed their HIV-positive status to a sexual partner. Women who disclosed to their sexual partners were 11 times more likely to be married or in a common-law relationship and 4 times more likely for their sexual partner or spouse to be the heads of the households. Frequency of condom use, belief that HIV disclosure is important for HIV prevention and control, knowledge of partner's HIV status, and number of sex partners were also significantly associated with disclosing to a sexual partner. CONCLUSION: This study found a low rate of disclosure of HIV-positive status by women to sexual partners and identified a number of factors associated with disclosure to sexual partners. These findings can be used in designing interventions that focus on individuals who have not disclosed their HIV-positive status to their sexual partners by demonstrating the importance of disclosure and safe sex practices.