To evaluate the effects of two regimens of recombinant human GH (rhGH) on growth, bone growth and bone mineralization in GH deficient children, we studied two groups (A and B), each including 16 GH deficient children matched for sex, age, body mass index, height, height velocity and bone age/chronological age ratio (BA/CA). Group A was treated with a weekly rhGH dose of 1IU/kg and group B with 0.5IU/kg. After four years of therapy, we evaluated the auxological outcome, bone morphometry (metacarpal index: MI) and bone mineralization by quantitative roentgen microdensitometry at the middle region of the II metacarpal and ultra-distal radius. Height increased significantly in both groups, being significantly higher in group A after four years of therapy, while BA/CA remained similar in the two groups. Bone growth (measured by the MI), and bone mineral density at the metacarpal (mostly trabecular bone) and at the ultra-distal radial (mostly cortical bone) site did not differ in the two groups, nor did these three parameters differ from normal controls. In conclusion, after four years a greater height gain was achieved by the higher dose of rhGH compared with the conventional dose, but there were no differences in bone growth and mineralization.