Basal plasma growth hormone levels as well as growth hormone levels during insulin -induced hypoglycemia have been studied in 19 cases with osteoporosis, in 34 patients with primary osteoarthrosis and in 19 control subjects. Women with primary osteoarthrosis had basal growth hormone levels significantly higher than control patients and patients with osteoporosis. The respective mean values and SE were: 4.9 +/- 0.8 vs. 1.9 +/- 0.8 and 1.3 +/- 0.2, p less than 0.025. During insulin-induced hypoglycemia the growth hormone levels rose to values which in osteoarthrotic women were significantly higher than in osteoporotics and in control subjects.