The aim of the present study was to examine cognitive performance and basic symptoms (BS) in the relatives of schizophrenic patients. The experimental sample comprised 24 first-degree relatives of patients. Each relative was matched to one control. Cognitive tests were: Continuous Performance Test (CPT), N-Back Working Memory Test (N-BACK), Negative Priming Test (NPT), and Span of Apprehension Test (SPAN). The Basic Symptoms Questionnaire (FBF) was used to measure subjective disturbances. The relatives showed only slightly worse cognitive performance than the controls, especially in the tasks with greater cognitive processing load. The relatives also revealed more BS than the controls in the domain of thought, attention, memory, language, and visual representation. Only CPT performance was hardly associated with BS. The negative correlation between FBF and CPT was strongly evident in the relatives with poorer processing capacity. This finding suggests that the BS are associated with sustained attention performance. Future research is needed to clarify whether BS are related to other cognitive domains.