Objectives: Cognitive dysfunction and posttraumatic stress disorder (PTSD) are common in methamphetamine patients. However, few studies have investigated the cognitive performance of methamphetamine patients with PTSD. The purpose of this study was to investigate the impact of comorbid PTSD on cognitive function in Chinese male methamphetamine patients.Methods: We analyzed 464 methamphetamine patients and 156 healthy volunteers. The PTSD Screening Scale (PCL-5) was used to assess PTSD and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was used to assess cognitive function.Results: Compared with healthy controls, methamphetamine patients had more cognitive dysfunction in imme-diate memory, visuospatial/constructional, language, attention and delayed memory. Moreover, methamphet-amine patients with PTSD had less cognitive dysfunction in immediate memory, attention, and delayed memory than methamphetamine patients without PTSD. Further stepwise regression analysis showed that PTSD alter-ations in arousal and reactivity cluster were risk predictors for language, and PTSD negative alteration in cognition and mood cluster were risk predictors for delayed memory.Conclusions: Our results indicate that methamphetamine patients without PTSD have poorer cognitive dysfunc-tion than those with PTSD. Some demographic and PTSD symptom clusters are protective or risk factors for cognitive dysfunction in methamphetamine patients.