BACKGROUND: Posttraumatic stress disorder (PTSD) has been associated with cognitive impairments, yet little is documented on the cognitive function of PTSD patients in Asian countries. It is shown that regular exercise can reduce PTSD symptoms, while no study has investigated the association between exercise and cognition in PTSD patients. This study aimed to examine cognitive functions of Japanese women with PTSD, and to explore the association between regular exercise and cognitive functions. METHODS: Forty-two women with DSM-IV PTSD and 66 demographically matched healthy control women participated in this study. Most of the patients developed PTSD after experiencing interpersonal violence. Cognitive functions were assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Regular exercise habit was assessed by a self-reported questionnaire. RESULTS: Compared to controls, PTSD patients performed significantly more poorly in all cognitive domains examined, including immediate memory, visuospatial construction, language, attention, delayed memory, as well as the total score of RBANS (all p < 0.001). Compared to PTSD patients without the habit of exercise, those who habitually exercised showed significantly better performance on delayed memory (p = 0.006), which survived after controlling for potentially confounding variables in a multiple regression model. LIMITATIONS: The cross-sectional design and relatively small sample size limited our findings. CONCLUSIONS: PTSD in Japanese women is associated with pervasively impaired cognitive functions, including notable impairments in verbal memory. Such memory deficits might be improved by regular exercise, although further studies are needed to investigate the causal relationship between exercise and cognition in PTSD.