Catatonia is a syndrome characterized by motor abnormalities that include excessive movements, reduced mobility, abnormal movements, reduced or other abnormalities of speech, reduced functioning, negativism, and reduced food or şuid intake. Catatonia is hardly recognized in child medicine. In fact, the catatonia syndrome is not rare, but it is covered under many guises. Its incidence in the adolescent psychiatric populations estimated in the range of 12 to 17%. It was reported in children and adolescents within autism spectrum disorders especially in those patients with self-injurious behaviors, and the repetitive behaviors in adolescents. Here we report an adolescent, who first presented catatonia and after diagnosed with autism spectrum disorder and discuss the clinical characteristics of catatonia in this population. The case was a 13-year-old female, who was brought to our department with complaints of refusal to eat, weight loss and social detachment for ten days. She had history of dyslexia and scoliosis. Family history was negative for any psychiatric disorder. At her first psychiatric assessment, it was observed that her self-care was poor and she was apathic in appearance. She was conscious, cooperating and oriented. Her mood was depressive and she had a limited affect. She was answering the questions by short sentences. She did not describe any delusions, hallucinations or illusions. Her psychomotor activity was severely decreased. Her parents reported that she did not eat anything and lost 6 kilograms in the last ten days and for the last month she spoke incessantly, expressing a few monotonous phrases had hand-washing behavior in a repetitive manner. Her physical examination and vital signs were in normal range. Complete blood count, electrolytes, as well as hepatic and renal function tests were in normal range except low potassium level. Extensive neurological examination, electroencephalogram and magnetic resonance imaging of the brain revealed no abnormalities. She had marked social deficits since early school years but this was the first time for the parents for seeking any psychiatric help. She was later diagnosed with autism spectrum disorder according to DSM-V. Autism spectrum disorder should be borne in mind in adolescents who have social deficits and refer with catatonia symptoms. To diagnose the underlying autism spectrum disorder is important for the treatment strategies and prognosis during follow up.