Background. Using data from a longitudinal study of young Australians, we applied recent international standards for overweight and obesity to examine associations with blood pressure (BP) and to determine the prevalence and degree of tracking of overweight and obesity. We also aimed to examine socioeconomic status in relation to these variables.Methods. BP, height, and weight were measured at 3-year intervals from age 9 to 18, and then at 25 years of age in a Western Australian cohort. At these stages, data were available for 1,036, 1,310, 618, 615 and 600 individuals, respectively.Results. We found 10% of 9-year-old males to be overweight or obese, while among 12-year-olds, 13% were overweight or obese; at age 15, and still at age 18, overweight or obesity was registered in 17% of this population and it rose to 42% among the 25-year-old young men. The percentage of overweight or obese females at these stages was initially 8, then 12 (at age 12), 11 (at age 15), 14 (at age 18) and finally 32. Overweight or obesity tracked to young adult life in 16% of those overweight or obese at 9, 24% at 12, 34% at 15 and 35% at 18 years. Systolic BP was significantly higher in the overweight or obese except in 12-year-olds. At the age of 25 years, 53% of men had high normal BP or were hypertensive.Conclusions. Increasing overweight or obesity in young Australians, consistent with international trends, has serious health implications. Overweight and obesity show tracking and are predictors of higher blood pressure, except in early adolescence. (C) 2004 Published by The Institute For Cancer Prevention and Elsevier Inc.