In April 1991, the Youth Risk Behavior Survey was administered to a sample of 1,412 high school students in Colorado public schools to collect information about priority health-risk behaviors among adolescents. Questionnaires were received from 1,170 students, a response rate of 83%. Classes in Colorado's 280 public schools were also selected to participate in the survey if they included 9th-12th graders; 68 classes out of 105 responded for a 65% response rate. The findings, based on unweighted data, revealed that over one-half of the students surveyed were sexually active; 60% of the males and 48% of the females reported using condoms during last intercourse. From 23% to 39% of sexually active students used alcohol or drugs before their last intercourse. Ten percent of high school seniors had been pregnant or had caused a pregnancy. Over 25% of the students rarely or never used seat belts. Nearly one-half of the male students indicated that they had carried a weapon within the past 30 days. Nearly one-third of respondents had seriously considered suicide; 19% had made a suicide plan, and 8% had attempted suicide. Females were at higher risk than males in all three categories. Eighty-five percent of respondents reported having used alcohol, with one-half indicating use within the past 30 days. Seventy percent indicated they had smoked cigarettes, with over one-quarter having smoked within the past 30 days. One-third reported having tried marijuana; 19% indicated they had tried other illicit drugs. These results suggest that Colorado high school students continue to engage in health-compromising behaviors at alarming rates. (NB)