摘要:Objectives. This study sought to describe condom use over time in new and established adolescent relationships. Methods. The outcome variable was time (in days) until first unprotected coital event. Analyses involved comparisons of Kaplan–Meier survival curves and Cox proportional hazards models. Results. Survival functions for the 2 relationship groups were significantly different. However, by 21 days the curves had converged: 43% of new and 41% of established relationships involved no unprotected coital events. Time to first unprotected coital event was significantly longer in new than in established relationships. Conclusions. Prolongation of condom use in ongoing relationships may be a useful intervention to prevent sexually transmitted diseases. Relationship characteristics exert strong influences on condom use. 1– 4 Intimacy, mutual trust, and presumed fidelity are elements of sexual relationships that influence condom use, 5– 9 contributing to lower rates of use in established relationships than in new relationships. 10, 11 The time required for a “new” relationship to become an “established” relationship in terms of condom use is therefore an important issue for prevention of sexually transmitted diseases (STDs). The objective of this study was to establish the length of time required for adolescent women to fail to use condoms on a consistent basis.