The Wisconsin Card Sorting Test (WCST) is one of the most widely used assessments of executive functioning related to prefrontal cortex. However, little is known about genetic and environmental determinants of individual differences in WCST performance. This study assessed heritability of standard WCST scores in a sample of 168 young female twins including 58 monozygotic and 25 dizygotic pairs. Several WSCT indices, including the number and percentage of errors, the number of perseverative responses, and the number and percent of perseverative errors, showed significant heritability ranging from 37 to 46%. The results suggest that selected aspects of frontal executive functioning measured by the WCST are moderately influenced by genetic factors.