Objectives: The rapidly rising incidence of plagiarism among students at universities throughout the world requires attention. This study aimed to determine the extent to which medical and nursing students in Erbil, Iraq, plagiarise, their knowledge, understanding and perceptions of plagiarism and the underlying factors that may lead them to plagiarise. Methods: This cross-sectional study was carried out between January and June 2017 among a sample of 400 undergraduate medical and nursing students at Hawler Medical University in Erbil. Plagiarism-related data were collected through a specially designed self-administered questionnaire. Results: In total, 280 (70%) medical students and 120 (30%) nursing students were included in the study. The reported prevalence of plagiarism was 54.3%, with a slightly higher prevalence among male students compared to female students (54.9% versus 53.8%; P = 0.820) and medical students compared to nursing students (58.9% versus 43.3%; (P = 0.004). Alarmingly, 34.8% of the students did not know what plagiarism was, and only 28% were aware of the legal consequences of plagiarism. Reported reasons for plagiarising included laziness and the ease with which others' work could be plagiarised, confusion, cultural reasons and pressure to meet deadlines. Conclusion: There was a lack of understanding of plagiarism and its legal ramifications among undergraduate medical and nursing students in Erbil. The findings of this study indicate that there is an urgent need to increase students' understanding of plagiarism and its consequences so as to reduce the incidence of this type of academic misconduct.