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The effects of dietary lysine on production performance, serum concentrations of metabolites, growth hormone (GH),insulin-like growth factor-I (IGF-I) and IGF-I mRNA expression in growing rabbits were examined. One hundred weaned New Zealand rabbits were allocated to individual cages and randomly offered a diet containing 5.5 (L1), 6.5 (L2), 7.5 (L3),8.5 (L4), or 9.5 g (L5) lysine per kg diet. The results showed that the average daily gain (ADG) of the rabbits from L3, L4 or L5 was higher than those from L1 or L2 (P0.05). The quadratic effects of lysine on the serum urea nitrogen (SUN) concentration was detected (P=0.035). Serum IGF-I concentrations had a trend to increase quadratically with the increasing dietary lysine (P=0.07). A significant correlation was found between serum IGF-I concentrations (x, ng mL-1) and ADG (y, g kg-1:y=-O.Ol7x2+ 1.984x+20.87 (R2=0.8982, P=0.O03). The relative abundance of hepatic and muscular IGF-I mRNA tended to increase with increasing dietary lysine levels (P=0.053 and 0.082, respectively). Providing the diets mainly consisted of corn, wheat bran and peanut vine, the most appropriate dietary lysine level for growing meat rabbits from weaning to 70 d old was found to be 8.5 g kg-1, and IGF-I may be an important factor controlling growth of weaned rabbits.