Ten years ago 8.4% of patients in French intensive care units (ICUs) were found to have severe sepsis or shock and 56% died in the hospital. As novel therapies for severe sepsis are emerging, updated epidemiological information is required. An inception cohort study conducted in 206 ICUs of randomly selected hospitals over a 2-week period in 2001, including all patients meeting criteria for clinically or microbiologically documented severe sepsis (with > or =1 organ dysfunction). Among 3738 admissions, 546 (14.6%) patients experienced severe sepsis or shock, of which 30% were ICU-acquired. The median age of patients was 65 years, and 54.1% had at least one chronic organ system dysfunction. The median (range) Simplified Acute Physiology Score (SAPS II) and Sequential Organ Failure Assessment (SOFA) at onset of severe sepsis were 48 (2-129) and 9 (1-24), respectively. Mortality was 35% at 30 days; at 2 months the mortality rate was 41.9%, and 11.4% of patients remained hospitalized. The median (range) hospital stay was 25 (0-112) days in survivors and 7 (0-90) days in non-survivors. Chronic liver and heart failure, acute renal failure and shock, SAPS II at onset of severe sepsis and 24-h total SOFA scores were the independent risk factors most strongly associated with death. Although the attack rate of severe sepsis in French ICUs appears to have increased over the past decade, its associated mortality has decreased, suggesting improved management of patients. Severe sepsis incurs considerable resources use, and implementation of effective management strategies and continued research efforts are needed.