The effect of dietary biotin supplementation, at a dose rate of 0.12 mg/kg bwt, on growth and growth rate of the hooves of 8 match-paired poines was investigated in a controlled feeding trial. Treatment animals had a mean hoof growth at the midline dead centre of the hoof capsule of 35.34 mm after 5 months of biotin supplementation compared to control animals 30.69 mm (P < 0.05). Comparison of regression analysis also showed that biotin supplementation produced a significantly higher (P < 0.02) growth rate of hoof horn in this trial. Treatment animals had a 15% higher growth rate of hoof horn and 15% more hoof growth at the midline dead centre, after 5 months of biotin supplementation compared to control ponies. No differences were found between feet for growth of horn, but the older animals in the trial had significantly lower hoof growth (P < 0.05) than the remaining poines.