Mental retardation is diagnosed before age of 18 that includes below-average general intellectual function and a lack of the skills necessary for daily living. It is also characterized with impairment of environmental adaptation and behaviors. Approximately, it affects 1-3 % of the general population. Studies have also shown a male preponderance for all types of mental retardation (MR) and males are 1.6-1.7 times more vulnerable as compared with females. Relative to the general population, people with MR are more likely to show psychosis, autism and attention-disruptive disorders and less apt to be diagnosed with substance abuse and affective disorders. Rates of Attention Deficit Hyperactivity Disorder (ADHD) range from 7% to 15% in children with MR. Behavioral problems are frequently detected and communication disorders are seen nearly 50% of people with MR. No data so far about the rate of suicide attempts in this group have been published. Aripiprazole’s mechanism of action is different from the other FDA-approved atypical antipsychotics (e.g., clozapine, olanzapine, quetiapine, ziprasidone, and risperidone). Rather than antagonizing the D2 receptor, aripiprazole acts as a D2 partial agonist. Aripiprazole is also a partial agonist of 5-HT1A receptor and like the other atypical antipsychotics displays an antagonist profile of 5-HT2A receptor. Aripiprazole is used increasingly for the treatment of ADHD, mood disorders, schizophrenia, conduct disorder, tic disorders, pervasive developmental disorders and anxiety disorders at child and adolescent psychiatry clinics. Aripiprazole is thought to be useful for psychiatric disorders affecting cognitive functions like ADHD because of its unique receptor binding profile. Aripiprazole has shown less adverse effects compared with other typical and atypical antipsychotics. Studies pointed that it causes minimal sedation, lesser metabolic side effects like weight gain and no alteration in prolactin serum levels. Here, we present a male case with 46,XY, YQ+ with borderline mental capacity, ADHD, Oppositional Defiant Disorder, Phonological Disorder and two suicide attempts while on the treatment with OROS methylphenidate at the dose of 18 mg/day. He was obese and had bilateral gynecomastia and some genetic stigmas like brachydactyly, clinodactyly, synophrys and low frontal hairline. He had used risperidone, haloperidole and quetiapine intermittently combined with methylphenidate since he was 5 because of his temper tantrums, impulsivity and stereotypic hand movements. All of these medications caused him weight gain and sedation during daytime; thereby his family discontinued these treatments due to these side effects. Of note, he has used methylphenidate for ADHD and found it useful for his attention at the school. We prescribed aripiprazole 5 mg/day treatment adjunctive to methylphenidate to control his temper tantrums, impulsivity and other behavioral problems. After starting aripiprazole he did not gain weight and feel sleepy at school. Moreover, his cognitive functions, social relationships and temper management were better than before as defined during routine controls at our clinic. His hand movements were not altered. In conclusion, it is likely that aripiprazole will be used in child and adolescent psychiatry clinics for many of the same target symptoms described earlier for risperidone.