Catatonia is a neuropsychiatric syndrome that can also occur depending on many general medical conditions, neurological diseases or certain drugs and characterized by hypokinesia, mutism, negativism, nutrition denial and posturing. Other than psychiatric disorders, about 30-80% of patients with catatonia are developing due to a general medical condition. In this paper, we report a case of catatonia occurring due to substance abuse and its successful treatment with electroconvulsive treatment (ECT). A 22-year-old female patient was admitted to our clinic for the last two days of inability to work, inability to speak, inactivity, food refusal, unwillingness to communicate due to loss of interest. On mental health assessment, reduction in patient self-care and verbal communication cannot be established that were observed. Her affect was blunted and apathetic Due to negativist and mutistic appearance of the patient we could not evaluate the other components of mental status examination. There was no psychiatric disorder in the patient’s history and family history. Symptoms of disease had started two weeks ago after the use of PAM (marijuana and magic mushroom) five to six times, with complaints of inability to recognize family members, confusion, reduction in speech rate and amount of talking, slowing of the movements, loss of appetite and these symptoms has been gradually intensified. Patient’s clinical picture was evaluated as catatonia, which is associated with the substance abuse and ECT was planned. All the symptoms of catatonia regressed after the fourth ECT session. The patient began taking food, negative attitudes have decreased, mutism disappeared and began to communicate with the treatment team. ECT treatment of the patient was completed and she was discharged on the seventh session. Symptom appearance of catatonia, caused by either psychiatric disorders or general medical conditions, does not change depending on the etiology. Therefore, medical and toxic reasons of catatonia must always be considered, because often multiple etiologic factors may be related to catatonia.