CONTEXT: Parents are encouraged to be the primary sex educators for their children; however, little is known about the accuracy of parents' views about condoms and oral contraceptives. METHODS: Telephone surveys using validated measures provided data on beliefs about the effectiveness, safety and usability of condoms and the pill among 1,069 parents of 13-17-year-olds in Minnesota and Wisconsin in 2002. Pearson chi-square tests and multivariate logistic regression models were used to compare beliefs according to sex, age, race, religion, education, income and political orientation. RESULTS: Substantial proportions of parents underestimated the effectiveness of condoms for preventing pregnancy and sexually transmitted diseases (STDs). Only 47% believed that condoms are very effective for STD prevention, and 40% for pregnancy prevention. Fifty-two percent thought that use prevents pregnancy almost all the time; 39% thought that the pill is very safe. Approximately one-quarter of parents thought that most teenagers are capable of using condoms correctly; almost four in 10 thought that most teenagers can use the pill correctly. Fathers tended to have more accurate views about condoms than mothers did; mothers' views of the pill were generally more accurate than fathers'. Whites were more likely than nonwhites to hold accurate beliefs about the pill's safety and effectiveness; conservatives were less likely than liberals to hold accurate views about the effectiveness of condoms. CONCLUSION: Campaigns encouraging parents to talk with their teenagers about sexuality should provide parents with medically accurate information on the effectiveness, safety and usability of condoms and the pill.