Catatonia, once solely attributed to schizophrenia, is now thought to be associated with many disorders. Autistic disorder shares some symptoms with catatonia, namely, mutism, echopraxia/echolalia, and stereotypies. Catatonia in autism may therefore be a variant of the autistic condition. However, organic deficits and psychiatric disorders, such as bipolar disorder, have also been linked with the manifestation of catatonia. Individuals with autism presenting with these comorbid conditions may therefore be at increased risk for catatonia. Little is written of the association of autism and catatonia to clarify the possibility of catatonia as a variant or a sign of a comorbid condition. The authors discuss three autistic patients and suggest specific etiologies for the symptoms of catatonia which presented in these cases. The therapeutic and diagnostic importance of comorbid disorders in autism is stressed.