Organic aspects of obsessive-compulsive disorder (OCD) have previously been described and hypotheses of biological etiology have been suggested. Sixty-one patients, 8-17 years of age, who fulfilled the DSM-III criteria for OCD in a review of the records were compared with 117 matched control patients for organic features. The indicators chosen for an organic concept were neurological signs, more than mild electroencephalographic abnormality, specific developmental disorder and attention deficit, and their defining property of an organic concept was confirmed by latent class analysis. Neurological signs was the most sensitive and specific indicator. Significantly fewer OCD children than control patients were assigned to the organic class. Almost all the types of obsessive-compulsive symptoms were more related to the non-organic class. Such extroverted symptoms as behavioral problems and loss of temper were significantly more frequent in patients assigned to the latent organic class, whereas symptoms of phobia and depressive mood were more often present in patients belonging to the nonorganic class. No difference was found between OCD patients and controls as to frequency of birth complications. The findings do not support the evidence of OCD having signs of major cerebral disturbance found by conventional neuropediatric methods.