A 13-year-old boy reported to the psychiatry department with a complaint of confusion, turning of head toward one side, urinary incontinence, and fever. The patient had had behavioral abnormalities and mental retardation since childhood. When his behavioral abnormalities worsened, his family members decided to take him to a psychiatrist. Three days previously, the patient was given oral paliperidone, 3 mg b.i.d., for behavioral abnormalities by a private psychiatrist. The first day after taking the medication, the patient had difficulty walking, reduced speech, and stiffness of the body. On the second day, the boy failed to recognize his family members; he was febrile, and he had urinary incontinence. He later came to us for further evaluation of his current problem. On general physical examination, he had a fever (103°F), elevated blood pressure (140/80 mmHg), and rapid pulse rate (120 bpm). Neurological examination revealed increased muscle tone in all four limbs, brisk reflexes, bilateral tremors of upper limbs, and positive Babinski's sign. Based on his history and the clinical examination, we made a provisional diagnosis of neuroleptic malignant syndrome (NMS), and the patient underwent a hematological investigation. On investigation, his hemoglobin was 12 g/dL, total leukocyte count was 16,200/mm3, differential count of neutrophils was 84%, and lymphocyte was 16%. The patient's erythrocyte sedimentation rate was 18 mm at the end of first hour and platelets were 1,052,000/mm3. The patient also showed decreased serum iron (8 μg/dl [reference range: 35–150]) and increased creatinine phosphokinase (2,120 U/liter [reference range: 35–232]). SGOT was 123 U/liter (reference range: 15–37) and SGPT was 86 U/liter (reference range: 30–65). His renal function, CSF analysis, and serum electrolytes were within normal limits. One of the incidental findings was increased head circumference (56 cm). The patient's CT scan showed congenital hydrocephalus. Later an assessment was made using the NMS scale;3 the score was 24/36. All these above findings strengthened our final diagnosis of NMS and made us immediately withdraw the oral paliperidone. Later on, the boy was managed with IV fluids, antipyretics, and benzodiazepines. The patient′s confusion decreased after a day of supportive management, and he reached a premorbid state within 1 week, with no neurological deficits at 3-week and 4-week follow-up visits. The parents were advised on behavioral management for temper tantrums. The patient was later referred to a neurosurgeon for management of congenital hydrocephalus.