This paper focuses on cardiovascular disease risk factors as they are influenced by sexual maturation. Serum total cholesterol, HDL-cholesterol, fasting triglycerides, blood pressure, height, weight and triceps skinfold thickness were investigated longitudinally in a population of 550 Norwegian adolescents aged 10-14 years at the onset. Two identical surveys were conducted, the first in 1979 and the last in 1981. Included in the study was a measure of developmental age, assessed by using sex maturity ratings formalized by Tanner. The physiological endpoints (except triglycerides) were more strongly related to developmental age than to age in years. Among 11 and 12 year old males, values not adjusted for sexual maturation stage underestimated height, weight and blood pressure and overestimated skinfold thickness, total cholesterol and HDL-cholesterol. In 15 and 16 year old males, unadjusted values overestimated height, weight and blood pressure, and underestimated total and HDL cholesterol. For females, unadjusted values underestimated height, weight, body mass index, triceps skinfold thickness and blood pressure among 11-12 year olds and overestimated the same variables for 15 and 16 year olds. These findings indicate that for adolescents, an index of physiological development more precise than chronological age should be included in epidemiological studies.