Treatment of growth hormone (GH) in idiopathic growth hormone deficiency (GHD) has been used over past 40 years. Outcomes of treatment including final heights are studied in several countries. Effectiveness of GH in idiopathic short stature (ISS) has also been reported by some studies. However, a difference of final heights with GHD and ISS is still not well understood. This study analyzes final heights of GHD and ISS patients. The study involves 17 patients with GHD (14 boys and 3 girls) and 6 patients with ISS (2 boys and 4 girls) treated in Ajou University hospital in Korea between January 2007 and July 2017. The mean bone age before GH start was 8.49 years (boys) and 7.33 years (girls) old in GHD. In ISS, mean bone age before GH start was 10.75 years (boys) and 9.38 years (girls) old. Mean final height of GHD is 168.45cm (male) and 155.33cm (female) while that of ISS is 165.3cm (male) and 154.08cm (female). Difference between target height and final heights of GHD is -0.48cm (male) and 0.83cm (female) while that of ISS is 1.45cm (male) and 1.33cm (female). To conclude, GH treatment is effective in both GHD and ISS. Patients with GHD have taller final height than ISS.