An increasing number of recent reports has pointed to the underlying neuropathological substrate for obsessive-compulsive disorder OCD. Neuropsychological tseting may suggest underlying organicity even though the neuroimaging studies and the neurological examination may be normal. Earlier reports are not in agreement about the laterality of deficits. Abnormalities in frontal regions, limbic areas and basal ganglia are noted in functional neuroimaging and neuropsychological studies. In closed head injury the damage tends to be diffuse, and it is not easy to clearly localize deficits or to determine their laterality. In this paper we review the various theories and literature on OCD and organicity, and report on four individuals who developed OCD symptoms after closed head injury. We also discuss their neuroimaging and neuropsychological testing results.