Brain natriuretic peptide (BNP) is involved in the regulation of blood pressure and fluid volume. It is used for the early diagnosis of heart failure (HF) in patients presenting to the emergency room with dyspnea. Interleukin-6 (IL-6) is a cytokine marker of inflammation that exhibits significant prognostic value in predicting severity and outcome of sepsis. Recently, it was suggested that inflammatory cytokines play an important role in the development of heart failure. Procalcitonin (PCT) is a propeptide of calcitonin which is normally produced in the C-cells of the thyroid glands. Although physiologic levels of PCT remain very low, a dramatic increase in serum PCT levels is observed during severe systemic infections. These properties make procalcitonin less useful for the diagnosis of simple infections but a very promising marker of severe infections especially in the critical care setting.