This study investigated the clinical characteristics of, and outcomes and risk factors for hospital mortality of 390 patients admitted with severe sepsis or septic shock in an intensive care unit (ICU). Prospectively collected data from patients collected between 1 July 2004 and 30 June 2006 were analysed. Overall hospital mortality was 49·7% and comorbidities were found in 40·3% of patients, the most common of which was haematological malignancy. The respiratory tract was the most common site of infection (50%). Hospital-acquired infections accounted for 55·6% of patients with Gram-negative bacteria predominant (68%). Multivariate analysis showed that acute respiratory distress syndrome, pulmonary artery catheter placement, comorbidities, hospital-acquired infection, APACHE II score and maximum LOD score, were independent risk factors for hospital mortality. In conclusion, severe sepsis and septic shock are common causes of ICU admission. Patients with risk factors for increased mortality should be carefully monitored and aggressive treatment administered.