Background. Disuse (рost-immobilization) osteoporosis is defined as secondary loss of bone mass in case of the absence or insufficient mechanical load on the skeleton. This di­sease can be associated with various risk factors, including long-time bed rest. The purpose of the research was to analyze modern lite­rary data on the mechanisms of development, principles of diagnosis and treatment of disuse osteoporosis and to present own clinical data of disuse osteoporosis in the patients with multiple injuries of the skeleton in the conditions of war in Ukraine. Materials and methods. The review was based on the analysis of literature sources from the PubMed, WOS, Scopus, Google, Google Scholar, Cochrane Library databases for the years 2007–2022. The search was conducted using keywords: disuse osteoporosis, immobilization, bed rest, bone mineral density (BMD), bone remode­ling, regene­ration. Results. The data on the theory of the mechanostat are considered as links in the appearance of disuse osteoporosis. In conditions of immobilization, bone remodeling processes are slowing down. Histomorphometric studies confirm a decrease in trabecular bone density, thickness of the cortical layer, and an increase in its porosity. A change in bone architecture with a biphasic course is observed. Disruption of the synchronicity of remodeling processes with a decrease in the rate of osteoblastoge­nesis and an increase in osteoclastogenesis was noted, and the role of osteocytes as mechanosensors was emphasized. Disuse osteoporosis leads to a violation of biochemical marker of bone meta­bolism. Early laboratory manifestations of bed rest were recorded in the form of a violation of calcium level, an increase in bone resorption markers, while bone formation markers did not change significantly. Bone loss in disuse osteoporosis is manifested by a decrease in BMD indices. The greatest decrease was recorded in the lower extremities’ bones and the vertebrae of the lumbar spine. Modern methods of treatment of disuse osteoporosis involve the use of antiresorptive and osteoanabolic agents but clinical data are limited, which requires multicenter randomized studies. The article presents 3 clinical examples of disuse osteoporosis after gunshot fractures of the lower extremities’ bones.