Objectives A core construct targeted by behavioural interventions is the perception that one is at risk for acquiring a sexually transmitted disease (STD). The objective of this analysis was to examine the role of intimacy on perceptions of risk for an STD (PRSTD) and condom use within late adolescent females' main relationships.

Methods A clinical sample of African–American women aged 14–19 years at enrolment were followed prospectively for 3 years. At each semiannual interview, participants reported their partner-specific PRSTD, feelings of intimacy, perceptions of partner's concurrency and condom use at last sex for each of their main sex partners.

Results A total of 285 individuals reported 724 main relationships. Using generalised estimating equations, intimacy was negatively associated with risk perception, after adjusting for perceptions of partner concurrency (OR: 0.68; 95% CI 0.60 to 0.76). PRSTD was no longer associated with condom use after adjusting for intimacy (OR: 1.30; 95% CI 0.83 to 2.02.

Conclusions Intimacy was found to be associated with risk perception and condom use within adolescent main relationships. Adolescents may not view their intimate partners as sources of infection. The success of individual-level STD prevention efforts, such as condom promotion, might be limited as condoms may be in conflict with adolescents' expectations about intimate relationships.