Working memory deficits are considered to play an important role affecting not only the pathogenesis but also the course of schizophrenia. Numerous studies of schizophrenic patients and their first-degree relatives suggest that this impairment may be an indicator of susceptibility to developing schizophrenia. OBJECTIVE A comparison of selected working memory indicators in patients with schizophrenia, their first-degree relatives, and healthy controls. METHODS Participants in the study were 99 patients with the diagnosis of schizophrenia (according to the ICD- 10-DCR criteria) in an early period of remission, their healthy first-degree relatives (N = 42), relatives with a history of psychiatric disorder (N = 14), and a control group of participants (N = 54) unrelated to the subjects and with no psychiatric history. Selected tests from the computer-aided Vienna Test Battery were used, measuring: reaction time (RT) in a task that required choosing among complex stimuli of two modalities, a tendency to perseveration (PERSEV), and immediate visuospatial memory span (CORSI). RESULTS Schizophrenic patients' performance was found to be significantly inferior to that of controls on all the cognitive tests related to working memory: they had a longer reaction time in forced choice tasks, elevated perseverative tendencies and reduced immediate visuospatial memory span. Moreover, healthy relatives of schizophrenic patients performed significantly poorer than did the controls both as regards perseverative tendencies and visuospatial memory scan. Schizophrenic patients did not differ significantly from their close relatives in the degree of visuospatial memory span impairment. CONCLUSIONS The findings indicate that working memory deficits as assessed by the tests used in the study may be related to familial susceptibility to schizophrenia. Therefore, the dysfunction may be taken into account in the capacity of endophenotype of such susceptibility.