This study aimed to assess the prevalence of contraceptive use by adolescents. A cross-sectional study was performed from March to September 2002 in a representative sample of adolescents 15 to 18 years of age in the urban area of Pelotas, Rio Grande do Sul State, Brazil. Multiple-stage sampling was used, and in the 448 census tracts located in the urban area, 90 were sampled and households were visited in each tract. Information was collected on sexual initiation and use of contraceptive methods. Chi-square test was used to compare proportions. The sample included 960 adolescents. 88% of subjects reported the use of any contraceptive method. Condoms were the most commonly used method (63.2%). Low adolescent schooling was the only variable associated with increased risk of non-use of contraceptives. Condom use was higher among males, adolescents whose mothers had 9 or more years of schooling, and those reporting several sexual partners in the previous year. Condoms were the most commonly used contraceptive method.