Male hypogonadism results from a failure of the testes to produce adequate androgen. Patients have low circulating testesterone in combination with clinical symptoms such as osteopenia, increased adiposity, decreased muscle mass, decline in energy and stamina, decreased cognitive function, decreased libido and erectile dysfunction. The cause may be primary (genetic anomaly) or secondary (defect in hypothalamus or pituitary), but often presents with the same symptomatology. Hypogonadal patients who are both symptomatic and who have clinically significant alterations in laboratory values are candidates for treatment. Testosterone replacement therapy is widely applied. The prevalence of eating disorders in men as compared to women is less than ten times and also shows differences in the course of the disease and the causes of its appearance. Social, genetic, psychological factors, personality traits and a history of trauma are considered to play a role in the development of anorexia nervosa (AN). In addition, steroid hormones affect the development of eating disorders and eating behavior. Homosexuality, asexuality and sexual role disorders are known to be more common in male patients with AN. AN is associated with notable medical complications and affects many systems like a general medical disease. One of the systems that is affected by AN is the genitourinary system; hypogonadism is one of the known complications of AN. Endocrine abnormalities such as hypogonadotropic hypogonadism mediate some of the clinical manifestations. Most of the endocrine changes that occur in AN are physiological adaptations to starvation and are usually reversible with weight gain. Prolonged AN or cachexia can cause hypogonadism. In this article we report a man, who had suffered from hypogonadism since infancy with no treatment and developed AN at age 18. Congenital hypogonadism with comorbid AN is a rare illness. As a result of the interaction of hypogonadism with anorexia nervosa the patient developed a sexual identity crisis, which is important in its clinical and theoretical aspects, since he suffered from delayed puberty, no secondary sexual characteristics, and no ejaculation or erection although he was 22 years old. Up to now only one case from Japan is reported in the literature with congenital hypogonadism and anorexia nervosa. Hypogonadism with comorbid anorexia nervosa has not been listed as a case in the Turkish indices yet.