Background Due to profound morbidity and a high rate of mortality in patients with acute respiratory distress syndrome (ARDS), identification of potential biomarkers such as nitric oxide (NO) is important to determine prognosis and guide clinical decision‐making. Methods and results: In this study, we included twenty-nine patients admitted to the Medical Intensive Care Unit diagnosed with ARDS caused by influenza A (H1N1) whose serum samples were collected on day 1 for determination of NO levels by GRIESS method. Simplified Acute Physiology Score (SAPS II) and Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring were performed on day 1 as well. The mortality in the observed patients was 55%. SAPS II and APACHE II scores were significantly higher (p < 0.05) in non-survivors as compared to survivors. There were no significant differences in gender, age, cigarette smoking and chronic pulmonary diseases between the survivors and non-survivors. As compared to non-survivors, the serum levels of NO were significantly higher in survivors (p < 0.05). Spearman’s rank correlation analysis indicated a significant positive correlation of SAPS II and APACHE II with NO. By using serum levels of NO, the receiver operating characteristic curve was plotted and the provided predictable accuracy of mortality (outcome) was 96%. Conclusion: The present study showed that measuring serum levels of NO in patients with ARDS (influenza A-H1N1) might be useful in predicting the clinical outcome.