To elucidate the cause of growth retardation, 14 cattle with renal tubular dysplasia (RTD) were investigated by determining serum growth hormone (GH) and insulin-like growth factor (IGF)-1 concentrations. Compared with 6 healthy cattle, the baseline, maximum, area under the curve and peak amplitude of serum GH concentrations were higher or tended to be higher. Serum IGF-1 concentrations were lower normal or lower in cattle with RTD than in healthy cattle. Serum IGF-1 concentrations correlated significantly with body weight and chest girth, but not with serum GH and creatinine concentrations. Growth retardation in RTD might be associated partially with GH resistance.