The NIOH consists of 11 key Sections: Analytical Services; Epidemiology; HIV/TB in the Workplace; Immunology & Microbiology; Information Services; Occupational Hygiene; Occupational Medicine; Pathology; Toxicology; Quality Assurance and SHE.

Each Section has a specific focus and provides services and training to stakeholders, clients and students. The Sections often collaborate on research projects relevant to the health of the South African workforce.

The primary functions of these Sections are: