Studies on the influence of sex hormones on cortisol responses to awakening and stress have mainly been conducted in adults, while reports on adolescents are scarce. We studied the effects of gender, menstrual cycle phase and oral contraceptive (OC) use on cortisol responses in a large sample of adolescents. Data come from TRAILS (TRacking Adolescents' Individual Lives Survey), a prospective population study of Dutch adolescents. This study uses data of 644 adolescents (age 15-17 years, 54.7% boys) who participated in a laboratory session including a performance-related social stress task (public speaking and mental arithmetic). Free cortisol levels were assessed by multiple saliva samples, both after awakening and during the laboratory session. No significant effects of gender and menstrual phase on cortisol responses to awakening were found, while girls using OC displayed a slightly blunted response (F(1, 244)=5.30, p=.02). Cortisol responses to social stress were different for boys and free-cycling girls (F(3, 494)=9.73, p<.001), and OC users and free-cycling girls (F(3, 279)=15.12, p<.001). Unexpectedly, OC users showed no response at all but displayed linearly decreasing levels F(1, 279)=19.03, p<.001) of cortisol during the social stress test. We found no effect of menstrual cycle phase on cortisol responses to social stress (F(3, 157)=0.58, p=.55). The absence of a gender difference in the adolescents' cortisol awakening response found in this study is consistent with previous reports. Our results further suggest that adolescent OC users display slightly blunted cortisol responses after awakening, and that gender differences in cortisol responses to social stress during adolescence are comparable to those described for adult populations, that is, stronger responses in men than in women. Whereas previous work in adults suggested blunted stress responses in OC users compared to men and free-cycling women, adolescent OC users showed no cortisol response. Effects of type of OC could not be studied because of low numbers of OC that were only progestin based.