The early detection and treatment of sepsis are the most important factors in improving the outcome of patients with this condition. However, many patients admitted to hospital experience a long delay in the diagnosis of sepsis. Furthermore, it is not uncommon for febrile patients to be sent home from the Emergency Department or the physician's office with the diagnosis of 'flu' only to return hours or days later in overt septic shock. The early diagnosis of sepsis may be challenging as many of the signs and symptoms are non-specific. Clinical studies suggest that early diagnosis of sepsis requires a high index of suspicion and comprehensive clinical evaluation together with laboratory tests, including a complete blood count with differential, lactate and procalcitonin levels.