The Bureau of Labor Statistics (BLS) developed the Occupational Injury and Illness Classification System (OIICS) to characterize occupational injury and illness incidents. OIICS was originally released in 1992. The BLS redesigned OIICS in 2010 with subsequent revisions in 2012. The OIICS includes four hierarchical coding structures: Nature of the injury or illness; Part of Body Affected by the injury or illness; Source and Secondary Source of the injury or illness; and Event or Exposure.

NIOSH in collaboration with the BLS has developed this web site and the accompanying downloadable software application as a resource for occupational safety and health researchers, policy makers, employers, and others who may need to use the OIICS for uniformly characterizing occupational injuries and illnesses or better understanding the national occupational injury and illness data released by the BLS and NIOSH (see About OIICS). To code or use the OIICS coded data one should properly understand the OIICS Coding Selection Rules.

This site provides graphical tree interfaces for the current OIICS version (v2.01) and the earlier version (v1.01) that was in use before the redesign. The coding trees are searchable and include descriptive details. The complete OIICS manuals are viewable as a separate document. In addition, standalone software versions of the coding trees are available for download and installation on your own computer desktop.

OIICS Coding Scheme Definitions
Nature: the principal physical characteristic(s) of the injury or illness.
Part of Body Affected: the part of the body directly affected by the previously identified nature of injury or illness.
Source and Secondary Source: the objects, substances, equipment, and other factors that were responsible for the injury or illness incurred by the worker or that precipitated the event or exposure.
Event or Exposure: the manner in which the injury or illness was produced or inflicted by the source of injury or illness.

Coding Selection Rules


Page last reviewed: December 9, 2023
Content source: National Institute for Occupational Safety and Health (NIOSH) Division of Safety Research