In a national telephone-based survey, information on sexual behaviour and outcomes were collected from 20091 randomly selected Australians in 2012-13. Data were weighted and analysed to determine the proportion of those who had received school-based sex education and to examine the associations between sex education and sexual health outcomes, specifically a history of a sexually transmissible infection (STI), early pregnancy, contraception use at first sex, and level of STI knowledge. Just over half the respondents (53%; n=19836) reported receiving sex education that included information about condoms and contraception. Using logistic regression analysis after adjusting for age, education and non-English-speaking background, we found that sex education was strongly associated with increased odds of using contraception at first vaginal intercourse (odds ratio (OR)=1.57; 95% confidence interval (CI) 1.44-1.71; P<0.001) and higher levels of STI knowledge (OR=1.75; 95% CI 1.46-2.12; P<0.001).