Non-alcoholic fatty liver disease (NAFLD) is more common in men than in women. Thus, it has been suggested that sex steroids do have a role in the development of NAFLD. The aim of the current paper is to illustrate the association between NAFLD and hypogonadism, by reviewing data derived from both human and animal studies. The prevalence of NAFLD is high in men with hypogonadism, including those with idiopathic hypogonadotropic hypogonadism (IHH), as well as in women in post-menopause, those under estrogen receptor antagonist treatment or women with Turner syndrome. Estrogens seem to play a pivotal role in hepatic lipid homeostasis, as demonstrated in animal models with diminished ovarian estrogens (i.e., ovariectomized mice) and low serum testosterone (T) concentration is independently associated with NAFLD. The elucidation of the exact role of sex steroids in NAFLD pathogenesis would create a unique opportunity to develop novel therapies to tackle NAFLD disease.