In 1986 and 1988, a structured questionnaire on sexual knowledge, attitudes, fears and behaviors was administered to 13, 15 and 17 year olds in Finnish public schools; 5289 (88% response rate) responses were recorded. With the exception of a few small differences in attitudes, no significant regional differences were recorded--suggesting that the results are representative of all Finnish adolescents. Except for 13 year olds, knowledge level was satisfactory. With increasing age, most attitudes showed increasing tolerance towards sexual matters and liberalism. Although several fears increased, AIDS was not perceived as an exceptionally great personal danger. By comparison with data from surveys 20 years previously, the age of first experience of sexual intercourse was lower--especially among women. About a third of the adolescents surveyed used no birth control and about 60% used a condom. Implications for educational policy and planning are discussed.