Background: Early sexual debut may be linked to reproductive health problems later in life. In addition,rnboth the timing of first sex and contraceptive use are affected by a variety of factors and this makes thernconsequences of youth sexuality much more serious. It is important to understand what influences youthsâ€Ÿrnsexual initiation, the need to use contraceptive methods and the consequences of these behaviours. Thesernmay affect the design and implementation of effective early pregnancy and disease prevention strategies.rnObjectives: The aim of this study was to determine the age at first sexual intercourse, contraceptive usernand related factors among female youths in Ambo town.rnMethods: A cross-sectional community-based study was conducted in Ambo town of West Shoa Zone,rnOromia Regional State between January and February, 2013. Two kebeles out of three were randomlyrnselected. Multistage cluster sampling technique was used to draw sample size of 675. Then, householdsrnwere selected by systematic sampling technique. Structured and pretested questionnaire and semirnstructured FGD guide was employed to collect data. Descriptive statistics such as frequencies, percentagesrnand graphs were used. To determine the association between dependent and independent variables, oddsrnratio with 95% confidence interval was computed. Logistic regression was also employed to assessrnpossible factors.rnResult: Overall, nearly half, 48.7% of the surveyed participants have ever had sex. The median age at firstrnsex being 17 years while; the mean Â± SD age was 16.7Â±2.1.Multivariate analysis showed that age group ofrn20-24[AOR= 7.35, (95%CI 4.80, 11.26)], those who attend, at least secondary education [AOR = 3.09rn(95%CI;1.44, 6.66)], those who encouraged by their friends to have boyfriend [AOR = 2.09 (95% CI;rn(1.42, 3.06), ever drank alcohol [AOR = 5.76 (95 % CI; 3.57, 9.31), and ever watched pornographicrnmaterials[AOR =1.78(95%CI; 1.19, 2.66)]were more likely to initiate sex.rnKnowledge of at least one contraceptive method was 95.4% and overall contraceptive current use wasrn37.3%. Multivariate analysis shows that age group of 20-24 [AOR= 3.22, (95%CI 2.08, 4.98)] and youthsrnwith partners who have discussed about the method [AOR= 2.15 (95%CI, 1.38, 3.34)] were more likely tornuse contraceptives. Currently unmarried [AOR= 0.17 (95%CI, (0.09, 0.31)] was less likely to userncontraception compared to currently married. As the qualitative data suggested, the perceived age at sexualrndebut among young girls is very early.rnConclusion and Recommendation: Substantial amount of female youths had started sexualactivity thatrnmight expose them to different reproductive health problems. Thus, early sexual initiation coupled withrnvery low contraceptive use among youth females is a potential risk of the development of sexual andrnreproductive health problems. Therefore, in view of our finding, an active effort to promote sexualityrneducation and contraceptive use should be intensified among female youths in the town, particularly youngrnwomen, in making informed decisions about sexual intercourse and contraceptive uses.