Eleven growth hormone deficient (GHD) subjects were treated regularly for 3 years with an authentic recombinant growth hormone preparation (0.35 to 0.5U/kg/week). Growth velocity (GV) increased from a mean o 2.91 +/- 1.58cm/year during the 1st year to 8.62 +/- 2.81cm/y in the 2nd and 7.63 +/- 1.84cm/y in the 3th year of follow up. During that period height age (delta HA) increased by 4.9 +/- 1 years while bone age advanced 4.3 +/- 1.4 year (delta BA) resulting in a delta HA/delta BA of 1.1 +/- 0.2. Since the height increment was associated with BA advancement the final height within normal range could not be attained. Thus, GHr therapy should be instituted before the height deficit would became intense as it happened in the majority of our patients. Early diagnosis and therapy of GHD is important, when growth retardation is less severe, in order to allow a better final height.