Objective: The aim of this study was to investigate the kidney growth and renal functions in children receiving recombinant human growth hormone (rhGH) treatment. Materials and methods: A total of 37 children who received rhGH for 1.5 years before the study was started and 48 healthy controls were included at first evaluation. Hormone levels were determined and kidney sizes were measured by ultrasound. Kidney functions were assessed by serum creatinine and estimated glomerular filtration rate (eGFR). After 3 years of first evaluation, 23 patients were re-assessed. Results: Kidney sizes were found to be lower in rhGH received children compared with controls at first evaluation (p<0.05). Significant positive correlations were found between anthropometric measurements and kidney length and kidney volume (p<0.05). Height was the most significant predictor of kidney volume in rhGH received children (p<0.001). After 3-years of follow-up significantly increases were found in kidney length and volume compared with the first measurements (p<0.05). Increase percentage of body height was similar to increasing percent of kidney length and liver long axis (14.2%, 11.7.1% and 7.7%, respectively, p>0.05). Although no abnormal renal function test results were found at first and second evaluations; rhGH received children had significantly lower eGFR, at first evaluation, compared with controls; however, renal functions significantly increased after 3 years of follow-up (p<0.05). Conclusions: In conclusion, effect rhGH treatment on kidney growth is parallel to growth in body height and other visceral organs. A 3-years rhGH treatment resulted in significant increases in renal functions.