Kallmann's syndrome (KS) is a form of hypogonadotropic hypogonadism associated with a defect in the sense of smell, due to abnormal migration of gonadotropin-releasing hormone-producing neurons. We report the case of a patient aged 16 years and 6 months who presented a micropenis with poor development of secondary sexual characteristics and anosmia. Plasma levels of luteinizing hormone, follicle stimulating hormone and testosterone were very low, while chromosomal analysis showed a 46XY karyotype. Hypothalamic-pituitary MRI showed bilateral agenesis of the olfactory bulbs associated with a 4 mm pituitary microadenoma. The patient was put on hormone replacement therapy with a good response.