The use of the index of working capacity in medicine and occupational safety makes it possible to assess the individual working capacity of workers, to predict the possibility of retaining workers in the profession. A survey using the ability to work index helps to identify personnel who have an increased risk of dismissal and absence from work related to health and poor work results. Various pathological conditions can take an employee out of work for different periods, but it is extremely important to understand whether it is possible to preserve the employee’s specialty and the prospects for his socialization. The disease changes not only the physical, but also the psycho-emotional state of the employee. The authors presented an analysis of modern scientific literature on the international experience of using the ability to work index to predict the possibility of returning to work in the specialty after treatment of diseases, rehabilitation. The work ability index can be used as a criterion for the effectiveness of treatment and rehabilitation after illness and subsequent employment. The link between quality of life and returning to work is of great importance. The ability to work of employees with various diseases, who have received different types of treatment, including surgical interventions, chemoradiotherapy and returned to work, is reduced compared with healthy employees. Recovery depends on the stage of the disease, the type of treatment and concomitant pathology. The risk of early retirement increases in the first years after cancer treatment. Professional rehabilitation promotes the fullest integration of an employee into society through professional self-realization.