The Kallmann syndrome is a very rare congenital association of gonadotropin-releasing hormone deficiency and hyposmia or anosmia. Clinically it is characterized by low serum concentrations of testosterone and inadequate low levels of luteinizing hormone and follicle-stimulating hormone as well as incomplete sexual maturation, lack of secondary sexual features (facial and body hair growth, deepening of the voice), micropenis and sometimes even cryptorchidism. The reduced or absent sense of smell is typical for the Kallmann syndrome and distinguishes this syndrome from other causes of hypogonadotropic hypogonadism. Additional findings may include synkinesia, hearing loss, unilateral renal aplasia, brachy- or syndactyly, agenesis of corpus callosum, cleft palate and dental agenesis. A 19-year-old man presented to our male infertility clinic with delayed sexual maturation, eunuchoid habitus, micropenis, cryptorchidism, erectile dysfunction and absence of ejaculation, anemia and osteoporosis as well as low serum concentrations of luteinizing hormone, follicle-stimulating hormone and testosterone in combination with hyposmia.