Pervasive developmental disorders (PDD) are characterized by two essential symptoms: impairment in social interaction, and restricted, repetitive, and stereotyped patterns of behavior, interests, and activities. PDD include autistic disorder, Asperger's disorder, and PDD-Not Otherwise Specified (PDD-NOS). These three disorders are sometimes termed autism spectrum disorders. A recent epidemiological survey demonstrated that the rate of PDD may be almost 1% and that many PDD cases might not be diagnosed properly in childhood. Erik Erikson described eight stages of psychosocial development through which a normally developing human should pass from infancy to adulthood. In the theory, an adolescent shows 'Identity vs. Role Confusion'. It has been reported that individuals with PDD often have identity crises which sometimes include gender dysphoria. This phenomenon might be related to the so-called identity diffusion in youth. When they reach their young youth, it has been said that subjects with PDD realize their uniqueness and differences compared to others, and, as a result, they may develop confusion of identity which could be exhibited as gender identity disorder. A recent study demonstrated that, amongst 204 children and adolescents who visited a GID clinic in the Netherlands, 7.8% were diagnosed with autism spectrum disorders after a careful diagnostic procedure by a multi-disciplinary team. Taken together, PDD and GID seem closely related to each other. In this paper, we present four PDD cases with gender dysphoria and related symptoms: 1) a girl with PDD who repeatedly asserted gender identity disorder (GID) symptoms in response to social isolation at school, 2) a junior high school boy with PDD and transvestism, 3) a boy diagnosed with Asperger's disorder who developed a disturbance of sexual orientation, and 4) a boy with Asperger's disorder and comorbid childhood GID. Many of the clinical symptoms related to gender dysphoria might be explained by the cognitive characteristics and psychopathology of PDD. The Japanese Society of Psychiatry and Neurology published guidelines for the assessment and treatment of GID in 1997, and revised them in 2006. As a result, GID has become well known as a clinical entity in Japan, and there have been an increasing number of Japanese patients complaining of gender dysphoria. It is important to consider an underlying diagnosis of PDD when encountering patients with gender dysphoria.