The aim of this article is to review the lessons on the relationship between GH and the principal metabolic cardiovascular risk factors that we learned from studies of GH deficiency (GHD) in the adult. The lesson that "organic" GHD has taught us is that primary impairment in the GH/IGF-I axis may lead to a high-risk cardiovascular profile that is partially reversible during GH replacement. Waiting for the definitive demonstration that GH substitution may reduce cardiovascular mortality in these patients, we find that data so far reported are encouraging and indicate in the beneficial cardiovascular effects of GH one of the major factors supporting this type of treatment in hypopituitary GHD adults. Moreover, enough evidence from GHD studies has been produced to suggest a physiological role for the GH/IGF-I axis in the control and regulation of several metabolic cardiovascular risk factors.