Objective: To verify serum procalcitonin levels of patients with acute respiratory failure secondary to influenza A (H1N1) upon their admission to the Intensive Care Unit and to compare these results to values found in patients with sepsis and trauma admitted to the same unit. Methods: Analysis of records of patients infected with influenza A (H1N1) and respiratory failure admitted to the General Intensive Care Unit during in a period of 60 days. The values of serum procalcitonin and clinical and laboratory data were compared to those of all patients admitted with sepsis or trauma in the previous year. Results: Among patients with influenza A (H1N1) (n = 16), the median serum procalcitonin level upon admission was 0.11 ng/mL, lower than in the sepsis group (p < 0.001) and slightly lower than in trauma patients. Although the mean values were low, serum procalcitonin was a strong predictor of hospital mortality in patients with influenza A (H1N1). Conclusion: Patients with influenza A (H1N1) with severe acute respiratory failure presented with low serum procalcitonin values upon admission, although their serum levels are predictors of hospital mortality. The kinetics study of this biomarker may be a useful tool in the management of this group of patients.