Schizotypal personality disorder is characterized by social and interpersonal deficits marked by discomfort with, and reduced capacity for, close relationships as well as by cognitive or perceptual distortions and eccentricities of behavior. Inappropriate or constricted affect, reduced capacity for relationships, lack of close friends and reduced capacity for social life are the symptoms that overlap both schizotypal personality disorder and autism spectrum disorders. The making of differential diagnosis may be difficult since several symptoms are similar between these disorders. In this study, we discussed the differential diagnosis issues on the basis of an adolescent case. Odd appearance, magical thoughts, reference thoughts suggests Schizotypal Personality Disorder whereas lack of eye contact at 2 years old, a preference to be isolated and play alone and referral to a child psychiatrist at 4 years old suggest Autism Spectrum Disorders. Based on the results of psychological assessment, Wechsler Intelligence Scale for Children-Revised (WISC-R) profile is compatible with autistic children's profiles. Based on Schizotypal Personality Questionnaire, the patient's anxiety, lack of close friends, constricted affect symptoms which take place in the category of interpersonal schizotypy seems to overlap with lack of communication of Autism Spectrum Disorders. This case report indicates that, separation of autism and schizophrenia, a very important historical breakthrough in autism research, may be blurred in cases with less typical clinical pictures representing autistic and schizophrenic "spectrum" diagnosis.