To investigate white matter abnormalities in patients with obsessive-compulsive disorder and to clarify the relationship between discrete white matter alterations and obsessive-compulsive symptom dimensions, the fractional anisotropy obtained from 25 male patients and 25 matched normal controls were analyzed. The patients had a significantly lower fractional anisotropy in the left anterior cingulate white matter than the controls. When stratified by clinical symptom dimensions, patients with a predominant aggressive/checking symptom dimension exhibited a significantly lower fractional anisotropy in the left anterior cingulate white matter, whereas patients with a predominant contamination/cleaning symptom dimension showed a significantly higher fractional anisotropy in the bilateral prefrontal white matter. Our findings provide evidence that obsessive-compulsive disorder may be a heterogeneous disease with distinct white matter changes.