It is important to consider the role that HIV infected individuals play in ongoing HIV transmission. Different anti-HIV treatment regimens may lead to variations in HIV transmission risk behavior among HIV infected individuals. HIV infected people with viral loads of less than 1,000 copies/ml are less likely to transmit HIV through heterosexual sex. However, condom use sometimes decreases after individuals start combination antiretroviral therapy (ART); also, some studies have shown an increased rate in acquiring sexually transmitted infections (STIs) following initiation of ART, and those on ART may transmit a drug-resistant strain of HIV. In the SMART study, participants were randomly assigned to one of two treatment groups: