Background: Mental health disorders are creating many psychosocial problems for nurses. Also, respect of professional ethics is an innate caracther in nursing practice. The aim of this study was to determine the relationship between mental health and respect of professional ethics among nursing staff.Method: In this descriptive and correlation study, the samples consisted of 195 nursing staff that were working in 2 governmental hospitals in Ahvaz. These hospitals were selected through simple randomized sampling method. Samples were selected through census sampling. Data were gathered by personal data scale, professional ethics scale and mental health scale) Symptom Check List-SCL90). Data were analyzed by descriptive and analytical statistics.Findings: Results showed that respect of professional ethics among nursing staff were 64.1% (relatively good), 21.5% (bad) and 14.4% (good). Dimensions of mental health including anxiety (R=-0.321), depression (R=-0.338) and psomatic complains (R=-0.292) had a significant relationship with professional ethics (P<0.05).Conclusion: Since professional ethics has a significant relationship with mental health, nursing managers should pay attention to professional ethics concept which leads to effected mental health of nursing staff.