Background: Identifying the predisposing factors of neck and shoulder complaints and finding solutions to avoid them could improve the occupational health condition of the nurses. In this study, we aimed at determining the role of psychological and physical occupational factors in developing neck and shoulder complaints among the participants. Methods: This analytic cross-sectional study was conducted on the nurses of main hospitals of Tehran. To study the prevalence of neck and shoulder pain, the Nordic questionnaire was used, and job content questionnaire was used to assess the psychological and physical occupational factors. Data were analyzed using SPSS and statistical methods. Independent sample t-test was used to compare the qualitative variables, and chi-square test was utilized for the statistical analysis of the qualitative variables. Results: Prevalence of neck and shoulder complaints among the nurses with high physical workload was significantly higher than in those nurses with low physical workload. Unlike physical workload, the prevalence of neck and shoulder complaints was not significantly different between the nurses with low or high psychological workload. Prevalence of neck and shoulder complaints among the female nurses was significantly higher than in the male nurses. In our study, only female nurses with high physical workload had been known as independent predictors of neck and shoulder complaints. Conclusion: Those nurses who had more workload, especially physical workload, had a higher prevalence of neck and shoulder complaints, and this fact could affect their work tasks.