This study aimed to assess the impact of the war in Ukraine on the mental health of individuals who had previously experienced the war in Bosnia and Herzegovina. A total of 649 respondents aged 35 and above, who were either directly recruited or indirectly affected as civilians during the war in Bosnia and Herzegovina, participated in this cross-sectional survey. The World Health Organization's Impact Event Scale (IES) and Self-Reporting Questionnaire (SRQ) were used to measure the impact of war events in Bosnia and Herzegovina and Ukraine on the respondents and to assess their mental health, respectively. The findings demonstrate a significant association between war events in Ukraine and the reactivation of post-traumatic stress disorder (PTSD) symptoms in individuals previously exposed to the war in Bosnia and Herzegovina. The results highlight the significant influence of the war in Ukraine on the reactivation of PTSD symptoms in individuals with prior exposure to the war in Bosnia and Herzegovina. Additionally, considering the various risk factors associated with PTSD reactivation, this study provides insights into the broader impact of war activities, including factors beyond the specific conflict in Ukraine.