This study aimed to investigate contraceptive use and its determinants in Kocaeli, Turkey. A questionnaire was applied to 922 randomly selected sexually active women of reproductive age, in order to extract information concerning contraceptive use and sociodemographic factors affecting behavior and contraceptive use. Knowledge of at least one method was nearly universal. Intrauterine devices and withdrawal were the most commonly used methods. Illiterate women and housewives had less knowledge about some modern methods. The number of children (p <0.001), nuclear type family (p <0.05), and approval of family planning (p <0.001) were the factors most predictive of contraceptive use. Husbands were involved in family planning via discussing family size (79.4%) and method (85.5%); 38.2% of males participated actively by using withdrawal or condom. Increasing the literacy of both male and female partners significantly increased both contraceptive use and the participation of husbands in family planning descision making. In conclusion, increasing the education level of couples and the status of women would result in increased contraceptive use in the future. Since the contraceptive behavior of women is influenced by their husbands' attitudes, family planning programs should be focused on the needs of both partners.