Today, restaurants are becoming increasingly concerned about the issue of Counterproductive Work Behaviours (CWBs). As a result, every restaurant strives to lessen the effects of these negative actions (Wallace & Coughlan, 2022). Employees' CWB propagation rates vary according to demographic characteristics (Uche et al., 2017). Therefore, this study examines the variances between fast-food restaurant employees' demographics, including gender, age, and marital status, regarding CWBs. This study's target population was employees working at fast-food restaurants in Cairo that serve fried chicken, burgers, and pizza. Because the questionnaire questions condemn the self, this study used an online questionnaire as the data collection instrument. This is because the participants' identity is hidden, ensuring their responses' credibility. The questionnaire was sent between July and August 2022 to about twenty fast-food restaurants in Cairo. About 12–15 employees from each restaurant responded. All told, 255 employees from all the restaurants responded to the survey. The questionnaire included eighteen items of CWBs (i.e., counterproductive work behaviours against individuals and counterproductive work behaviours against the organization). The results indicated that in fast-food restaurants, older employees are less likely to engage in both dimensions of CWBs than younger employees. Female employees are also less likely to engage in both dimensions of CWBs than male employees. Moreover, marital status showed no difference in CWB dimensions between fast-food restaurant employees. This research will give fast-food restaurant managers an overview of the CWB phenomenon and the employees' demographic variances regarding these behaviours.