Aims. Stress is one of the most important phenomena in recent century and has an important effect on the psychos o mat health. Based on clinical experiences, the most important problem of nursing students is stressors of clinical environment. This study was to evaluate the nursing students' knowledge about stressors of clinical environment.

  Methods. This study performed on 120 students of two nursing faculties of Tehran city. Data collecting tool was a questionaire included 114 questions about stress rate of patients' physical care, interpersonal relationship with patients and their families, education and care staffs and encountering to environmental factors.

  Results. The most stress related to physical care of patient (100%) in students of third term. The statistical chi-square test showed that there was a significant correlation between different terms (P<0.05).

  Also, the stressor factors were encountering to environmental factors, contact to educational & care staffs and interpersonal relationship with patient and their families But, there was no statistical significant correlation between different terms.

  Conclusion. To improve the educational level of nursing students on encountering the environmental stressor factors, it is essential to review and modificate the qualification of educational courses.