An estimated 21% of injection drug users (IDUs) in Pakistan are HIV-positive and data suggest that the spouses of IDUs may be a critical component of the HIV transmission chain. This study interviewed 101 spouses of male IDUs about their sexual practices and drug use. We found that 43% had been sexually active with their partners in the past month but only 4% reported selling sex. Almost a quarter (23%) used drugs and 19% injected drugs, usually a combination of diazepam and pheniramine. Although sex work was infrequent among spouses of IDUs, their risk of contracting HIV and transmitting it to others was high because they received injection drugs, sometimes along with their IDU husbands, from the same health centres that provided therapeutic injections to the rest of the community. IDU spouses may thus serve as a bridge group via therapeutic injections, rather than via sex work.