The effect of therapeutic ultrasound (US) on the growth plates of growing bone was determined through fluorescence labelling and histopathological evaluation in one-month-old rabbits. Mean growth rates and mean heights of the growth plates of the US exposed radius vs. control radius, and US exposed ulna vs. control ulna showed no statistically significant differences at all intensities and time intervals. Mean growth rates and heights of the growth plates of the US exposed radius for 0.2 W/cm2 (SATA) US vs. 0.5 W/cm2 US showed the same type of pattern compared to those of the control radius for 0.2 W/cm2 vs. 0.5 W/cm2 at days 10, 15 and 20. Similar results were also found for the ulna. Effects of 0.5 W/cm2 US on the mean growth rates and mean heights of the growth plates were superior to those of 0.2 W/cm2 US at day 10. The results at day 10 were reversed for the same comparisons at days 15 and 20. No cavitation effect of US was observed on growth plate cells. There was no evidence of partial or complete premature closure of the growth plates or of angular deformity of the carpal region. © 2002 Elsevier Science Ltd. All rights reserved.