Context. Acquired adult growth hormone deficiency (GHD) is a rare condition, with increased metabolic and cardiovascular risk. The dynamic GH evaluation is indicated in patients affected by organic hypothalamic/pituitary disease with no more than 2 hormone deficiencies or in patients with history of head injury, cranial irradiation, subarachnoid haemorrage or hypothalamic disease with multiple pituitary hormones deficiency. Nevertheless, clinical picture related to GHD may be subtle including unexplained infertility. Objective. We have retrospectively evaluated the indication to GHRH plus arginine test in our monocentric cohort of patients treated with hrGH. Patients. They were 94 subjects: 44 females and 50 males, aged 19-67 years. The GHRH+arginine test was performed in 29 pts with organic hypothalamic/pituitary disease and in 4 for Childhood onset-GHD (Co-GHD). In other patients the diagnosis was suspected for: metabolic syndrome (n=23), osteoporosis (n=6), heart disease (n=7), fatigue (n=12), hypogonadism (n=6), unexplained infertility (n=6), hypoglycemic crises (n=1). Interventions. Retrospective study. Methods. Analysis of the indication to GH dynamic test and the etiology of GHD in our casuistry. Results: In the group of females <50 ys (n=22), the indication of infertility was 8%, while the most prevalent indication was metabolic syndrome (27%). 10 patients had idiopathic GHD while others have an organic hypothalamic/pituitary disease: 3 patients with Co-GHD, 1 patient with post-surgery treatment, 2 patients with Sheehan’s Syndrome, 5 patients with empty sella and 1 patient with non-secreting pituitary microadenoma. In this group the IGF-1 levels were <1.5 percentile of age-related subjects in 10% of patients, <50 percentile in 55% and>50 percentile in 35% of patients. In the group of males <50 ys (n=21), the indication of infertilty reached 19% (n=4). The etiology of GHD was related to organic hypothalamic/pituitary disease (5 postsurgical patients, 3 pts with empty sella, 1 pt with Arnold-Chiari malformation and 1 pt with pituitary apoplexy) and idiopathic disease (n=10). IGF-1 levels were <1.5 percentile of age-related subjects in 31% of patients, <50 percentile in 50% and>50 percentile in 19% of patients. Conclusions. These observations suggest that idiopathic GHD may be unrecognized due to its subtle manifestations and that an extended use of dynamic GH test may reveal such condition, expecially in infertile males.