The corpus callosum is the main transverse tract of neural fibers that connects the two cerebral hemispheres. It is made of more than 200 million nerve fibers. The primary function of the corpus callosum is to integrate motor, sensory, and cognitive activity between the left and right hemispheres. Corpus callosum agenesis (CCA) is among the most common brain malformations observed in humans. Its incidence varies as a function of both diagnostic techniques and sample populations: in the general population, its estimated prevalence is 3-7 per 1000 birth, while in children with developmental disabilities it is 2-3 per 100 . It has been associated with a number of neuropsychiatric disorders, from subtle neuropsychological deficits to pervasive developmental disorders. According to these various disorders, treatment of these conditions involves many psychopharmacological agents. At this case presentation, we report a 14 years old female, who has CCA and moderate mental retardation; have been treated successfully with atomoxetine for Attention Deficit Hyperactivity Disorder (ADHD) and skin picking behavior. A 14-year-old girl, admitted to our policlinic 15 months ago with the complaints of skin picking and inattentiveness, had moderate mental retardation and CCA. She has been receiving special education. A while before she had metylphenidate treatment for the attention problems. However she had not benefited from treatment. So we started atomoxetine treatment 0,3mg/kg/day and then we have raised the dose to 1,2 mg/kg/day, gradually. Attention functions were better but skin picking problem did not improve until the dose was titrated up to 1,2mg/kg/day. She tolerated the drug well. Skin picking behavior and attention deficit symptoms have improved approximately in 3 months. Patients with CCA may have severe neuropsychiatric problems such as; epilepsy, mental retardation, developmental delay, autistic features. In our case she had moderate mental retardation, ADHD and skin picking behaviour. In our case atomoxetine treatment was used because of intolerance to metylphenidate. In literature, there is no information about therapeutic effect of atomoxetine on skin picking behaviour. CCA is among the most common brain malformations observed in humans. Although the clinical manifestations differ; mental retardation and seizures are often. However we may need to develop different pharmacological therapy strategies for the rare situations accompanying CCA.