AbstractObjectivesRapid-onset obesity with hypoventilation, hypothalamic dysfunction, and autonomic dysregulation (ROHHAD) is a rare, potentially fatal, pediatric syndrome.Case presentationsWe describe three cases of ROHHAD-syndrome in Greece. The main and earliest symptom was the excessive and rapid weight gain at 5, 2, and 3 years of age. Years after the onset of obesity, the patients developed hypothalamic dysfunction with various endocrinological abnormalities (at 9, 8, and 6.8 years, respectively), autonomic dysregulation and finally, alveolar hypoventilation (at 14.6, 8, and 7.8 years, respectively), leading to the diagnosis of ROHHAD-syndrome.ConclusionsThe rarity of the syndrome, the variable symptoms’ presentation, and the lack of specific diagnostic tests could explain why no previous cases have been reported from our country. The rapid onset of obesity was underestimated, and the patients were misdiagnosed with other more common obesity syndromes. Therefore, we propose a questionnaire to help physicians identify patients with ROHHAD-syndrome.