1. An experiment with 9 dietary supplemental biotin concentrations (0, 0.03, 0.06, 0.09, 0.12, 0.15, 0.18, 0.21, 1.5 mg biotin/kg) was conducted to study the effects of supplementary dietary biotin on growth performance and foot pad dermatitis (FPD) of White Pekin ducklings from hatch to 21 d of age. 2. One-d-old male Pekin ducklings (n=576) were randomly divided into 9 dietary treatments, each containing 8 replicate pens with 8 birds per pen. Final weight, feed intake and body weight gain increased with increasing dietary biotin levels from hatch to 21 d of age. No differences were observed in feed conversion ratio. 3. The supplemental biotin requirement of ducklings for optimal body weight gain was estimated to be 0.180 mg/kg. 4. At 28 d of age, dehydration, cracks, bleeding and scab, and ulceration were observed in biotin-deficient ducks. The external scores for FPD decreased from 17.50 to 1.00 with increasing dietary biotin. It was concluded that supplemental dietary biotin should not be less than 0.21 mg/kg to minimise the incidence of FPD.