The paper deals with the connection between accidents and occupational diseases due to the weak application of ergonomics in business practice. Applying the principles of ergonomics in the day-to-day running of companies in primary prevention makes it possible to prevent the occurrence and exacerbation of difficulties in the musculoskeletal system of the employees concerned, which can ultimately avert the development of occupational diseases and increase occupational accidents. Ergonomics primarily addresses work environment factors that are cumulatively pathogenic, so their impact on employees will only become apparent after a specific exposure time. In contrast, occupational safety and health focus primarily on thermal and traumatogenic factors of the work environment, which can cause an employee an occupational injury of varying severity or result in death. To comprehensively cover the effects of all work environment factors on employees, the work environment and the work activity itself must be assessed from both occupational health and safety and ergonomics. The observance of ergonomic principles in the solution of workplaces makes it possible to prevent many different costs related to the occurrence of accidents at work and occupational diseases. In most cases, however, these are cost-effective solutions whose effect is not immediately visible, so they are more likely to be reached by companies that apply sustainability principles or have a positive experience of the past. The article focuses on the need to implement ergonomic principles in business practice, such as preventing occupational accidents and developing occupational diseases.