Our aim was to investigate whether neurological impairment in chronic Behçet's disease (BD) patients with normal appearing brain can be assessed by means of diffusion-weighted imaging (DWI). The averaged apparent diffusion coefficient (ADC) values were calculated in 22 different radiologically normal appearing brain regions in 32 patients with and without neurological findings and 20 control subjects. The ADC values in bilateral frontal, temporal and occipital normal appearing white matter were significantly higher in the patient groups compared with the control subjects (p < 0.05). In these brain regions, DWI revealed differences in the ADC values between patients with neurological findings (including symptomatic and neuro-Behçet patients) and the asymptomatic patient group. The similarity of the ADC values of patients without symptoms to those of the control group allowed clear discrimination between patients with and without neurological findings. DWI may serve to assess subclinical neurological involvement in BD, even when structural changes are absent.