To identify ways to improve prevention of mother-to-child transmission (PMTCT) of HIV, we conducted a cross-sectional study of 1,092 HIV-infected men and women attending an AIDS support organization in Jinja, Uganda, between October 2003 and June 2004. Pregnancy risk behavior was defined as having sex without contraceptive or condom. Overall, 42% of participants were sexually active, 33% practiced pregnancy risk behavior, and 18% desired more children. Men were almost four times to want more children than the women (27% vs. 7%). Among those practicing pregnancy risk behavior, 73% did not want more children and were at high risk for unwanted pregnancies. Although 81% knew that mother-to-child transmission of HIV could be prevented, only 22% believed that an HIV-infected woman who received PMTCT therapy could still deliver an HIV-infected child. Lack of MTCT information, having attended the program for </=2 years and desire for children were independently associated with pregnancy risk behavior. PMTCT and other HIV prevention and care programs should ensure provision of family planning for HIV-infected populations who do not want to become pregnant.