Sequential gadolinium-DTPA (Gd-DTPA) enhanced MR images were obtained before and after steroid therapy in a case of neuro-Behçet's disease. Multiple scattered lesions, which could not be detected on pre- and post-contrast CT, were demonstrated mainly in the white matter of the pons and/or the cerebrum with both T1- and T2-weighted images. Some of these lesions, however, were not enhanced at all by infusion of Gd-DTPA. The Gd-DTPA infusion study demonstrated marked enhancement in the white matter of the pons and cerebrum. Some lesions not seen with T2-weighted images were also strongly enhanced by Gd-DTPA infusion at the acute stage. After steroid therapy, the symptoms and abnormal laboratory findings were resolved. The pontine and cerebral lesions on plain MR images remained unchanged even after resolution of the symptoms, suggesting that they were inactive old foci. On the other hand, the lesions detected in the enhancement study before steroid therapy disappeared with the repeat Gd-DTPA enhanced MR images hich were performed after resolution of the symptoms. Some active inflammatory lesions in neuro-Behçet's disease may be demonstrated only on Gd-DTPA enhanced MR images. Gd-DTPA enhanced MR imaging appears to be potentially useful for detecting active inflammatory lesions in neuro-Behçet's disease and for evaluating the efficacy of treatment.