Fifty children, aged less than or equal to 10 years, with isolated fractures of the femoral shaft had scanograms performed at fracture union and a mean 39 years later (SD, 1.6 years). Overgrowth was a mean 6.9 mm (95% confidence limits, 5.2-8.6 mm). Age was an influential variable, over growth being less in children < 4 and those > 7 years. At fracture reduction, much less shortening should be accepted than is commonly recommended.