Abstract
The purpose of the study was to identify the relationship between Human Resources Management system (HRM system), vertical trust, and job involvement. This type of involvement in work is considered very important for an organisation because it affects the added value generated employees. It is also associated with the well-being felt by individuals and testifies to the satisfaction of their psychological needs. The study was conducted on a group of 227 employees of large and medium-size entities. The application of the Structural Equation Modelling (SEM) made it possible to confirm the relationship between the HRM system and job involvement with the mediating role of vertical trust in the examined relationship. In order to verify to what extent the job involvement variation can be explained by the HRM system, a multi-dimensional linear regression analysis was applied.