GHRH is effective in improving the growth velocity in GHD children. Atenolol is a beta adrenergic antagonist which acutely inhibits somatostatin secretion. To determine whether the combined therapy of GHRH+Atenolol improves the growth response to GHRH in GHD children we studied in a double blind, randomized trial 11 prepubertal GHD children (5F, 6M) divided in 2 groupS:Group A n=5 (3F,2M), chronologic age (CA) X 8±2.7 years, bone age (BA) X 4.9 ± 2.8 years received daily GHRH 20 ug/kg sc + daily oral Atenolol (1mg/kg). Group B n=6 (2F, 4M) CA X 10.6±3.7 years, BA X 5.5±2.9 years received baily GHRH 20 ug/kg sc + placebo. The children were admitted to the hospital before and after 1 year of treatment to meassure GH every 20 minutes for 24 hours and height was determined every 6 months. Growth velocity increased in group A from 3.3 ± 0.6 cm/year to 6.7 ± 1.2 cm/year (p<0.0005) and in group B from 3.2 ± 0.8 cm/year to 5.4 ± 1.4 cm/year (p<0.025). Growth velocity was significantly different in group A compared to group B (p< 0.05). Mean 24 hour GH secretion increased in group A from 1.8 ± 1.1 to 2.2±1.2 ng/ml (NS) and in group B from 1.2 ± 0.14 to 1.6 ± 0.4 ng/ml (NS). This study demonstrate that the beta-adrenergic blockade with Atenolol enhances the growth velocity to GHRH in GHD children.This suggests that the growth velocity in GHD children treated with GHRH can be potentiated with an agent that blocks Somatostatin secretion.