OBJECTIVE To determine whether growth hormone (rhGH) affects bone mineral metabolism and bone mineral content (BMC, g/cm) in a therapeutic trial of recombinant growth hormone in growth retarded children with juvenile chronic arthritis (JCA) treated with steroid. METHODS BMC was measured in 20 children (of whom 17 were treated with corticosteroid) before and after one year of rhGH. Children were randomized to receive either low dose (12 IU/m2/week) or high dose (24 IU/m2/week) for one year. Three monthly assessments were made of disease activity and anthropomorphic measurements. Blood and urine samples were also obtained to measure indicators of disease activity, bone remodeling, and vitamin D and parathyroid hormone (PTH) status. RESULTS BMC increased during the treatment period and correlated with increasing height. Osteocalcin levels, normally indicators of bone formation, increased after rhGH treatment and correlated significantly with height velocity, particularly for the high dose treatment group. In contrast, osteocalcin levels were negatively correlated with C-reactive protein levels, both before and during treatment. Height velocity, vitamin D, PTH, and osteocalcin levels were significantly lower than age matched controls before treatment. CONCLUSIONS Steroid treated children with both JCA and severe growth retardation have reduced vitamin D, PTH, and osteocalcin levels. After treatment with rhGH, height velocity increased, as did BMC. Growth hormone might be a useful adjunct in the treatment of severe growth retardation and osteoporosis in children with JCA. The longterm benefits of rhGH in the treatment of osteoporosis remain unclear.