Swedish population reference standards for height, weight and body mass index (BMI) attained at 6 to 16 years (girls) or 19 years (boys) are presented. Data were obtained from two independent nationwide samples of Swedish children; one (740 children) born in 1955, the other (2907 children) born in 1967. The weights of the children born in 1955 were adjusted to equal those born in 1967; heights did not differ. These reference standards refer therefore to Swedish children born at around 1970. The observations were fitted by the power transformation, or L, M, S method of Cole and Green. Weights and BMIs were thus normalized and valid SD scores for individuals obtained. Centile charts are given for clinical use. The means of the present, nationwide standards were 1-2 cm and 1-2 kg greater than those of the Solna-based standards currently in use.