OBJECTIVE: Critical illnesses are a significant public health issue because of their high rate of mortality, the increasing use of the Intensive Care Units and the resulting healthcare cost that is about 80 billion of dollars per year. Their mortality is about 12% whereas sepsis mortality reaches 30-40%. The only instruments currently used against sepsis are early diagnosis and antibiotic therapies, but the mortality rate can also be decreased through an improvement of the patient's nutrition. The aim of this paper is to summarize the effects of vitamins A, B, C and E on the balance between pro-oxidants and anti-oxidants in the critical care setting to confirm "a beneficial care enhancing". MATERIALS AND METHODS: The peer-reviewed articles analyzed were selected from PubMed databases using the keywords "critical care", "intensive care", "critical illness", "sepsis", "nutritional deficiency", "vitamins", "oxidative stress", "infection", and "surgery". Among the 654 papers identified, 160 articles were selected after title and abstract examination, removal of duplicates and of the studies on pediatric population. Finally, only the 92 articles relating to vitamins A, C, E and the B complex were analyzed. RESULTS: The use of vitamins decreased morbidity and mortality in perioperative period and critically ill patients, especially in ICU. Among the most encouraging results, we found that the use of vitamins, both as monotherapy and in vitamins combinations, play a crucial role in the redox balance. Vitamins, especially vitamins A, C, E and the B complex, could help prevent oxidative damage through the breakdown of the oxidizing chemical chain reaction. CONCLUSIONS: Even if the results of the studies are sometimes discordant or inconclusive, the current opinion is that the supplementation of one or more of these vitamins in critically ill patients may improve their clinical outcome, positively affecting the morbidity and the mortality. Further, randomized studies are required to deeply understand the potentiality of a vitamin supplementation therapy and develop homogeneous and standardized protocols to be adopted in every critical care scenario.