Patients with autosomal recessive polycystic kidney disease (ARPKD) may have growth retardation that is disproportionate to the degree of renal dysfunction. We treated growth-retarded ARPKD patients with recombinant growth hormone (rhGH) and document the response to therapy and effect of rhGH on the rate of progression of renal failure. The diagnosis of ARPKD and congenital hepatic fibrosis was made on the basis of clinical findings and by abdominal ultrasound examinations. Seventeen patients (6 girls/11 boys) aged 0.3-18.3 years were studied. Diagnosis was made prenatally in 6, after birth in 3, and in 8 between 0.33 and 10 years. Follow-up was 2 months to 14.3 years (median 6.9 years). Growth, growth velocity, weight, and bone age were measured before and after treatment with rhGH. Insulin-like growth factor-1 and IGF binding protein 3 were measured prior to rhGH therapy. Five children (1 girl/4 boys) with height Z-scores < or =1.2 (5/17) aged 4.5-11.9 years received rhGH therapy. Duration of rhGH therapy was 0.3-5.4 years. All responded to rhGH (Z-score before -2.8 vs. -1.26 after treatment, P=0.03). An increase in height Z-score was noted 0.5-1.5 years after starting rhGH therapy. There were no side effects from rhGH therapy. The initial Z-score in the untreated group was -0.35 and the final score was -0.64. Initial glomerular filtration rate (GFR) in the treated group was 77 versus 104 ml/min per 1.73 m(2) in the non-treated group. GFR in 3 of 6 growth-retarded patients (<5th percentile) was 38, 65, and 30 ml/min per 1.73 m(2). GFR in 2 of 11 non-growth-retarded patients was 30 and 26 ml/min per 1.73 m(2). The change from initial GFR and final GFR in treated patients was 77 versus 76 ml/min per 1.73 m(2), and non-treated patients 104 versus 89 ml/min per 1.73 m(2) ( P>0.05). Growth failure in ARPKD may be attributable to factors other than chronic renal insufficiency alone. Use of rhGH therapy in ARPKD is safe, effective, and has the potential to improve the physical and psychological well-being of these children.