Adults with either GH deficiency (GHD) or GH excess have bone, metabolic, and somatic impairments. This review deals with available data on the relationship between GH status, bone mass, articular disorders, and body composition. GHD subjects have reduced bone mineralization and increased fracture rates. Acromegalic artropathy occurs in virtually all patients and in its late degenerative stages may resemble osteoarthritis. Abnormalities in GH/IGF-I were observed in patients with different forms of arthritis. When concerning body composition (BC), both severe and partial GHD are characterized by increased fat mass, especially truncal, and reduced lean mass. In acromegaly, an increase in body weight, lean mass, and extracellular water, and reduced fat mass were observed; these abnormalities did not always disappear after the normalization of GH/IGF-I levels. On the contrary, long-term GH replacement at physiological doses improved the abnormalities in BC and increased bone mineral density in men with adult-onset GHD, but discordant data were obtained for the bone effects in women. In conclusion, both GHD and GH excess are responsible for some well-defined alterations in metabolism, BC, bone mass, and joint physiology. Their normalization (by GH replacement or treatment of acromegaly) reverses most of these abnormalities, thus confirming their GH-related etiology.