Purpose: This study was to investigate sexual behavior, pregnancy and contraception knowledge among teenage. Method: The subjects were 627 of teenaged girls from 14 to 19 years old who lived in a capital city. Data was collected by questionnaire surveys used the convenience sampling. The instrument used for this study was contraception knowledge tool. The collected data was analysed by using descriptive statics, chi-square, t-test, ANOVA, Duncan test for post hoc with SPSS program. Result: The finding of Sex experience was kiss and petting experience 196(32%), sex intercourse 44(7.2%) and pregnancy 6(1%). Average of contraception knowledge was 3.8 score(total 15). Statically significant general characteristics variable related to sex experience were age, school type, smoking and alcohol use. Statically significant general characteristics variable related to contraception knowledge were age, school type, previous sex education and contraception education. Conclusion: These results of this study provided health professional informations to develop intervention programs to reduce teenage pregnancy.