Objectives: The aim of this study was to investigate workplace violence by patients or their relatives towards health-care workers in Congolese hospitals. Methods: Through the autumn of 2012, a cross-sectional survey on workplace violence was conducted in a sample of 2,210 registered health-care workers (989 males and 1,221 females, aged 33 ± 8 years) from 436 hospitals located in the province of Katanga, Democratic Republic of the Congo. Verbal aggression, harassment and physical violence perpetrated by patients or their relatives within the previous year along with factors contributing to violence, were recorded, and the response rate was 99%. Results: About 80.1% of the health-care workers had experienced one or more types of workplace violence. Overall, the severity of workplace violence varied from verbal aggression (57.4%) and harassment (15.2%) to physical violence (7.5%). Patients were the major perpetrators of verbal aggression and harassment, whereas patients' relatives were mainly involved in physical violence. The frequency of workplace violence was similar across hospitals. Male health-care workers were more likely to be victims of physical violence, whereas female health-care workers were the prime target for harassment. Only 34.3% of the violent episodes were reported to a supervisor. Furthermore, disrespect for medical deontology was the main cause of workplace violence perceived by 68.8% of the health-care workers. Conclusions: Although it has not been officially recognized, there has been workplace violence towards health-care workers perpetrated by patients or their relatives despite the fact that health-care workers have traditionally been highly respected in Congolese society. Further studies on this issue may suggest opportunities for combating violence in Congolese hospitals.(J Occup Health 2015; 57: 69–80)