This review focuses on new aspects in growth hormone (GH) biology and pathophysiology presented at the Endocrine Society's meeting, in San Diego, in June 2010. First, we will describe recent advances in the understanding of cytokine hormone signaling via STAT5 in mammary gland development, highlighting the primary role of miR193b for differentiation of mammary stem cells into alveolar progenitor cells. We will examine the potential implication of endocrine and autocrine GH for mammary gland carcinogenesis. Three novel murine models bearing tissue-specific inactivation of GH receptor or JAK2 bring new insights into the large spectrum of GH effects on energy homeostasis. We will also report new data supporting a paracrine regulation of GH secretion in women by estrogen's action in the brain. Thereafter we will question the reasons for GH abuse for doping by assessing the hormonal impact on body composition and physical performance in recreational athletes. Finally, we will discuss the controversial issue of GH replacement in acromegalic patients presenting GH deficiency after treatment of acromegaly.