A very rare syndrome of rapid-onset obesity with hypoventilation, hypothalamic dysfunction and autonomic dysregulation (ROHHAD) has been recently described as causing morbidity due to hypothalamic dysfunction and respiratory arrest. Its prognosis is poor and often cardiac arrest occurs due to alveolar hypoventilation. This disorder can mimic genetic obesity syndromes and several endocrine disorders. We present a 13-year-old female patient who was reported to be healthy until the age of 3 years. She was admitted to our emergency department, presenting with respiratory distress. Features matching ROHHAD syndrome such as rapid-onset obesity, alveolar hypoventilation, central hypothyroidism, hyperprolactinemia, Raynaud phenomenon and hypothalamic hypernatremia were detected in the patient. In addition to these features, the patient was found to have hypergonadotropic hypogonadism and megaloblastic anemia. Because of its high mortality and morbidity, the possibility of ROHHAD syndrome needs to be considered in all pediatric cases of early-and rapid-onset obesity associated with hypothalamic-pituitary endocrine dysfunction.