Background: Individuals with heightened risk for psychosis demonstrate difficulties in cognitive functions. However, concerning specific cognitive domains, some results have been replicated while others have not. We aimed to investigate the neuropsychological functioning of subjects with familial risk for psychosis in a population based birth cohort. Methods: The subjects of the study were members of the Northern Finland 1986 Birth Cohort. All cohort members having a parent with psychosis or A-type personality disorder according to the Finnish Hospital Discharge Register were invited to participate in the study during years 2007-2009 (28% of whom participated). A 2% random sample of the rest of the cohort members were invited as a control group (46% of whom participated). 74 familial risk and 79 control subjects were included in the analyses after excluding the subjects having had a psychotic episode according to the Structured Interview for Prodromal Syndromes (SIPS). The neuropsychological assessment consisted of five tests of Cambridge Neuropsychological Test Automated Battery (CANTAB): Paired Associates Learning (PAL), Spatial Working Memory (SWM), Stockings of Cambridge (SOC), Rapid Visual Information Processing (RVP) and Information Sampling Task (IST). Results: Our results show that one form of executive functioning - spatial planning, as assessed by SOC - is worse in the familial risk group compared to the control group (p=0.047). Visual learning and memory (PAL), working memory (SWM), attention (RVP) and decision making (IST) did not differentiate these two groups. Discussion: Spatial planning, a complex cognitive function depending largely on prefrontal brain processes, is impaired in persons with genetic vulnerability for psychosis. Future follow-up of these individuals will show whether this finding has value in predicting conversion to psychosis.