The objective of this study was to examine the influence of chronic toxic encephalopathy (CTE) on Trail Making Test (TMT) performance, with special focus on the discriminative potential of this test. We assessed TMT performance in patients diagnosed with CTE, patients with similar symptoms but no diagnosis, and healthy participants. Inferior performance was seen in CTE, and increasing age had a negative effect on TMT performance only for the CTE group. This effect was most pronounced in TMT-B. However, the ability of the TMT to identify CTE was low, whereas all healthy participants were identified as healthy. Thus, the sensitivity of TMT alone was low, but it succeeded in correctly classifying normal subjects. The pattern of results indicates that normal TMT performance may be seen in individuals with mild to moderate brain syndromes, such as CTE, whereas poor performance should not be expected in healthy individuals.