Free and Easy Wanderer Plus (FEWP) is a traditional Chinese medicine that has been used to treat stress- and depression-related diseases in China. To study the effects of FEWP on post-traumatic stress disorder (PTSD), the present study investigated how chronic treatment with FEWP affected rodent behaviors in a modified single-prolonged stress and shock (SPS and S) model, which induces certain behavioral manifestations similar to those seen in PTSD patients. Locomotor activities (LMA), elevated Plus Maze (EPM), and Morris Water Maze (MWM) tests were used to determine its effects on general locomotion, anxiety and cognitive functions following traumatic exposure. The results showed that SPS and S impaired performance in MWM and produced anxiogenic-like effects in EPM, both of which were significantly ameliorated by chronic treatment of FEWP at doses of 5 and 10 mg/kg/d. The effects of FEWP were not due to changes in locomotion. The current findings provide strong evidence that FEWP may be a useful drug for treating PTSD. Key words: Single prolonged stress and shock, post-traumatic stress disorder, Morris water maze, open field, elevated plus maze.