Objective: The objective of this study was to assess the emergence of posttraumatic stress symptoms (PTSS) in Greek health care professionals during the COVID-19 pandemic. Method: A cross-sectional study was conducted via an online survey from April 10 until April 13, 2020. The survey included sociodemographic questions and the following psychometric tools: the Peritraumatic Distress Inventory, the Posttraumatic Stress Disorder-8 questionnaire, the Brief Patient Health Questionnaire Depression scale, the Athens Insomnia Scale, and 3 questions about negative perceptions of COVID-19. The survey was distributed through social media and comprises part of a larger survey targeting the general population. Altogether, 270 health care professionals responded to the survey. Results: Health care professionals appeared to be moderately stressed from the COVID-19 crisis, with women scoring higher on all clinical scales and the difference between women and men being statistically significant. Criteria for a probable posttraumatic stress disorder diagnosis were met by a total of 16.7% (21.7% of women; 5.1% of men). Negative emotion and threatened or physical tension are positive significant predictors of PTSS. Those suffering with higher levels of PTSS scored positively for insomnia and exhibited significantly higher peritraumatic distress. Conclusion: Health care professionals could benefit by being screened for PTSS and insomnia. (PsycInfo Database Record (c) 2020 APA, all rights reserved).