Introduction:The muscle atrophy is one of the most important and frequent problems observed in patients in Intensive Care Units. The term describes the disorder in the structure and in the function of the muscle while incidence rates range from 25-90 % in patients with prolonged hospitalization.Purpose:This is a review containing all data related to the issue of muscle atrophy and is especially referred to its causes and risk factors. The importance of early diagnosis and early mobilization are also highlighted in the study.Material and methods:a literature review was performed on valid databases such as Scopus, PubMed, Cinhal for the period 2000-2013 in English language. The following keywords were used: loss of muscle mass, ICU patients, immobilization, bed rest.Results:From the review is concluded that bed rest and immobilization in order to reduce total energy costs, are the main causes for the appearance of the problem. The results of the reduction of the muscle mass mainly affect the musculoskeletal, cardiovascular and respiratory system. The administration of the cortisone, the immobility, the sepsis and hyperglycemia are included in the risk factors. The prevention is the primary therapeutic agent and this is achieved due to the early mobilization of the patients, the use of neuromuscular electrical stimulation and the avoidance of exposure to risk factors.Conclusions:The prevention of muscle atrophy is a primary goal of treatment for the patients in the ICU, because it reduces the incidence of the disease, reduces the time spent in ICU and finally improves the quality of patients’ life.