Objective: To determine the compliance among adolescents and measure the associations of various demographic and behavioral factors with compliance with a standard hepatitis B vaccination series. Design: Eight hundred twenty six patients from a hospital-based adolescent medicine clinic were enrolled. The participants received a standardized education about hepatitis B and the immunization schedule (0,1, and 6 months) and filled out questionnaires investigating demographic factors, risk behaviors, risk factors for obtaining hepatitis B, medication use, chronic illnesses, and experience, knowledge and attitudes about hepatitis B and the immunization series. They then received their first hepatitis B vaccination. Compliance is being followed and is defined as having received the second vaccine within 61 days and the third vaccine within 274 days of enrollment. The associations between the dependent and independent variables were measured using chi square analysis with Mantel-Haentszel test for trend for ordinal covariates, followed by a stepwise logistic regression analysis. Results: 28.5% are male. 18.5% are white, 45.6% black, 20.4% Hispanic, 1.4% Asian, 14.2% other. 18.5% are self-pay, 33.4% Medicaid, 9.7% free care, 38.4% private insurance. The age range of patients is 11.1-24.9 years. 49.9% were compliant with the second vaccine. 46.7% of those who could have been compliant with vaccination 3 were compliant. Factors associated with compliance with the second vaccine on bivariate analysis are female gender (P<0.001), white race (P<0.001), presence of an eating disorder (P=0.043), knowledge that hepatitis B is sexually transmitted (P=0.015), increased travel time to the clinic (P=0.029), the use of birth control pills (P=0.002) and vitamins (P=0.048), knowing someone who had received the series (P=0.018), and academic achievement(P=0.030). Factors associated with noncompliance include Medicaid(P<0.001), marijuana use (P=0.020), and cocaine use (P=0.048). Logistic regression modeling reveals that the covariates with compliance are white race(OR=3.84, 95% CI=2.47-5.96), female gender (OR=1.70, CI=1.20-2.40), knowledge that hepatitis B is sexually transmitted (OR=2.16, CI=0.91-5.12), and self-reported academic achievement (OR=1.12, CI=1.00-1.26).Conclusion: 49.9% of adolescents are compliant with the dosing schedule for the second hepatitis B vaccination. Knowledge of factors related to noncompliance may facilitate targeted interventions for reaching teens at risk.