Constipation is a side effect of antipsychotic drugs that have high affinity to muscarinic cholinergic receptors. In some severe cases, constipation progresses to ileus and bowel ischemia, and causes multiple morbidity and mortality related to sepsis and perforation especially among patients with schizophrenia. In this report, a colonic ileus case is described in a patient diagnosed with schizophrenia under the treatment of paliperidone palmitate. A 38-year-old, single, unemployed man, graduated from primary school was brought to Ankara Ataturk Hospital Psychiatry Clinic by police in November, 2013. His relatives told about his problems as abstaining from being out of home, having weight loss, diminishing his self-care skills and stacking the waste. Paliperidone palmitate 150 mg intramuscular and biperiden 2 mg/day treatment was given to the patient and he was hospitalized for further treatment. With the diagnosis of schizophrenia, second dosage of paliperidone palmitate 100 mg intramuscular treatment was given to the patient one week after first dosage. Due to the fact that the patient had constipation, nausea, vomiting, abdominal distention and colonic liquid-gas level finding in his abdominal x-ray, he was counseled to the general surgery department. Loop ileostomy operation was performed and the patient was discharged after operation. In conclusion, ileus is an important side effect of antipsychotic treatment, with potentially morbid and mortal consequences if early detection fails. Complete physical examination and close screening of side effects are recommended when antipsychotics are prescribed. In addition, preventive actions should be promoted and appropriate interventions should be provided when needed.