A total of 33,413 infants born in Jerusalem between 1964 and 1971 were followed up at 17 years of age by matching computerized database files. A logistic regression model was used to estimate the odds ratios for being overweight at 17 years of age for 500-g birth weight categories from less than 2500 g to 4500 g or greater. Information on the ethnic origin, paternal education, birth order, maternal age, and area of residence at birth was available, and these factors were used as possible confounders. The adjusted odds ratios for being overweight (greater than or equal to 90th percentile; body mass index greater than 24.6 kg/m2) and severely overweight (greater than or equal to 97th percentile; body mass index greater than 27.8 kg/m2) at 17 years of age was elevated for the three birth weight categories above the normal reference category of 3000 to 3499 g, with an estimate of 2.16 and 2.30 for male subjects with a birth weight greater than 4500 g and 2.95 and 4.39 for female subjects. The data suggest that higher birth weights correlate strongly with being overweight in late adolescence independently of other factors considered. However, the predictive power of this association is poor.