The association between growth failure and serum IGF-I levels has been assessed in 32 children with Juvenile Chronic Arthritis (JCA) aged 5-16 years. A spectrum from normal growth to severe growth failure was included in the study population. Height Standard Deviation Score (SDS) ranged from -5.79 to +1.41 (median -1.22) and Height Velocity from 0.72-8.85 cm/yr (median 3.81 cm/yr). Known risk factors for growth failure (disease activity, steroid treatment, vertebral collapse) were confirmed. Additionally, height SDS was significantly correlated with serum IGF-I levels (rs = 0.49; p = 0.008); height velocity was significantly, although less strongly correlated with IGF-I levels (rs = 0.41; p = 0.027). There was no correlation between IGF-I levels and either of two indices of nutritional status, or between IGF-I levels and current steroid dose. The correlation of serum IGF-I with parameters of growth failure may be due to either insufficient secretion of growth hormone (GH) or defective GH action. In view of the recently increased availability of GH for treatment of short stature, it is important to distinguish between these two mechanisms.