Over the past years, studies of unaffected first-degree relatives of schizophrenic patients have reported cognitive deficits in the domains of executive functions, memory, and attention. However, these deficits may rely on lower level information processing deficits. Here, we investigated visual information processing with a visual backward masking task. A vernier target was followed by a grating mask. Observers had to indicate the offset direction of the vernier. We determined the SOA between the vernier and the grating onset for schizophrenic patients, their healthy first order relatives, and a healthy control group. Schizophrenic patients needed SOAs about three times longer than healthy controls to reach a predefined criterion level. Backward masking performance of unaffected relatives was significantly better than the one of patients but significantly worse than performance of controls. This result adds further evidence that low level deficits as determined by visual backward masking are endophenotypes of schizophrenia.