Introduction Errors are inevitable in medical practice and this issue has attracted the attention of healthcare systems worldwide. Therefore, it is of utmost importance to pay attention in educational systems. The present study aimed to investigate the frequency and cause of nursing students’ errors. Methods This descriptive study conducted based on a cross-sectional design. The researcher provided nursing students with a questionnaire. The participants were selected through a purposive sampling method. Eventually, the collected data were analyzed by SPSS17. Results The mean value of errors in students was 32.83 ± 28.5 and the prevalence rate of the errors ranged from 0 to 175. In total, 2922 errors were reported by the students, the most frequent of which were wearing the same pair of gloves for the care of more than one patient (2.61 ± 2.83), negligence to wash the hands (2.41 ± 2.95) and clean the thermometer before utilization (2.19 ± 4.68). Moreover, errors in oxygen therapy (0.69 ± 1.03) and medication (0.87) obtained the lowest frequency. Furthermore, most of the students’ errors were due to not having enough knowledge about medicines (2.1 ± 7.4), lack of appropriate equipment (2.6 ± 1.7), and poor clinical skills (2.1 ± 5.6). Discussion and conclusion: The most frequent nursing students’ errors are related to hand hygiene and personal protection. In addition, the lack of enough skills and appropriate equipment are prevalent causes of nursing students’ errors. Authorities in this field should attend to these errors in nursing education, clinical practice, and nursing studies in order to promote this profession in all of these three dimensions.