This study investigated the patterns of student use of school-based health centers (SBHCs) in Oregon. The study explored adolescents' health care needs and use of services, the reasons students use SBHCs for care, and the type of students who use SBHCs; the study also assessed the relationships between use of SBHC services and student risk behaviors, and compared health care access and behaviors of students using SBHCs with those of other students. High school students attending schools with and without SBHCs completed the Youth Risk Behavior Survey, and a summary and evaluation of SBHCs. Findings indicate that students use SBHCs for easy access, financial reasons, and privacy protection, and that students from areas of lower socioeconomic status, minority groups, and older age groups are more likely to use SBHCs. Access to SBHCs is related to increases in the health care of students. While SBHCs are providing care to some of the highest risk students--as indicated by experiences of abuse, drug use and sexual behavior--these students are not engaging in higher levels of alcohol or cigarettes than other students, and SBHC users report lower rates of sexual activity without birth control and are more concerned about HIV/AIDS than their peers. (Tables and figures of statistical data are included.) (JPB)