Objective: To evaluate the efficacy of recombinant growth hormone for increasing adult height in children treated for idiopathic isolated growth hormone deficiency (IGHD). Design: Observational follow up study. Setting: Population based registry. Participants: All Albanian children diagnosed with idiopathic isolated growth hormone deficiency and attained final height. Their treatment started between 2001 and 2011. Main outcome Measures: Annual changes in height, and change in height between the start of treatment and adulthood. Results: 71 patients were diagnosed with idiopathic isolated growth hormone in the period mention above. Adult height was obtained for 13 (13.3%) patients. The male: female ratio was 9:4. HAZ score at the start of treatment was -4.69±1.18. The mean dose of growth hormone at start of treatment was 0.21 IU/kg/week for 3 patients and 0.24 IU/week for 10 patients. Height gain was 2.31±0.75 z-scores, resulting in an adult height of -2.15±0.99 z-score (girls, -2.25±1.50 z-score; boys, -2.11±0.78 z-score). Patients who completed the treatment gained 2.31±0.75 z-score of height in 4.54±2.14 years. Conclusion 69.2% our patients with idiopathic isolated growth hormone deficiency treated with growth hormone able to achieve their genetic height potential. Despite starting treatment late, they managed to gain 2.31±0.75 HAZ score in height and the final height for majority of them was within the target height range. This study highlighted the importance for early diagnosis and treatment in children with growth hormone deficiency. This is to ensure adequate duration of treatment to optimize the prepubertal growth so that height prognosis of these children can be further improved.