Objective: To identify what variables influence having multiple sexual partners. Methods: A cross-sectional study was carried out with 542 women of two higher education institutions from the northwest of Mexico, who answered a questionnaire measuring psychological variables underlying high-risk sexual behaviors. The data were analyzed with T-tests, Mann-Whitney U tests, and with a multiple linear regression. Results: A multiple linear regression analysis showed the following results: for women from Hermosillo, Sonora, the predictors of high-risk sexual behaviors were biological age, age of sexual debut, and one biological state - «I was physically excited»-, with those variables explaining 53.4% of the total variance; for women from Ciudad Juarez, Chihuahua, the predictors were biological age, and two types of biological states -«I was physically excited» and «I was under the influence of alcohol», explaining 20.8% of the total variance. Conclusions: The results underscore the need to design prevention programs directed to avoid HIV infection based on behavioral competencies training.