Growth in height was studied in 58 patients with juvenile rheumatoid arthritis (JRA) followed for 4.9 +/- (SD) 2.8 years, who had never received steroids. Height measurements were converted to Height Z Scores. Height Z scores at first and at last visit were respectively 0.7 +/- 1 and 0.7 +/- 0.9 (NS) in pauciarticular, 0 +/- 1.6 and -0.55 +/- 1.6 (p = 0.045) in systemic, 0.29 +/- 0.8 and -0.4 +/- 1 (p = 0.0001) in polyarticular JRA patients. In systemic and polyarticular patients a significant negative relation was found between the duration of disease and the delta Height Z score (p = 0.0008) as well as between the sum of the periods of active disease and the delta Height Z score (p = 0.0001). The patients with functional class = 1 lost 0.01 +/- 0.19 Height Z score per year while those with functional class > or = 2 lost 0.16 +/- 0.13 Height Z score per year (p = 0.005). The loss of Height Z score in systemic and polyarticular subjects observed during pubertal age (-0.71 +/- 0.67 Height Z score) was significantly (p = 0.02) greater than in those observed before puberty (-0.1 +/- 0.72). The longer duration of disease, the higher degree of functional joint involvement, and the age of puberty appear to be risk factors for height growth impairment in systemic and polyarticular JRA.