In recent years, the effect of critical conditions on intestine and the role of such changes in maintenance and progression of systemic disorders are of particular attention. This issue is relevant in critically ill neurosurgical patients too. Intestine morphology and microbiome changes in these patients represent a wide field for researches in intensive care and prevention of secondary damage to other organs and systems. This review ensures a current approach to the problem of intestine morphology and microbiome changes in critically ill neurosurgical patients. We reviewed the data from clinical studies and experiments reproducing a critical condition in animals. Most publications are indexed in the PubMed, e-library, Google Scholar databases. We also analyzed the data from NEJM, JAMA, Lancet, Critical Care and other issues. The manuscript contains an overview of 44 foreign and 13 domestic references; over 50% of researches were published within the past 5 years. Searching depth was over 50 years.