Patients with cerebral microangiopathy (n = 17), acute and chronic left hemisphere (LH) stroke (n = 18, n = 21) and normal controls (n = 41) were studied in 2 simple visual detection tasks, one with predictable, the other with unpredictable targets. Eye movements were registered by means of infrared light reflections (pupil-corneal reflection method); the points of visual fixation were continuously calculated by a microprocessor system. Patients with cerebral microangiopathy showed primarily difficulties in holding attention, as reflected by pathologically short durations of gaze on target, frequent unsuccessful anticipations and a high overall number of fixations. In contrast, acute LH stroke patients were characterized by a deficit in shifting attention, as reflected by prolonged latencies and long search durations due to many intervening search fixations. By means of a nonparametric discriminant analysis procedure, about 90% of patients with microangiopathy and about 80% of acute LH stroke patients were reliably distinguished from normal controls. The differences between these two patient groups were most pronounced in the simpler task with predictable targets. Among those patients discriminated from normals, about 96% were correctly reclassified as belonging either to the microangiopathy or to the acute LH stroke group on the basis of their abnormal eye movement variables alone.