The Ontario Association of Pathologists (OAP) is the oldest pathology organization in the country, founded in 1937 with the aim of promoting excellence in Pathology and Laboratory Medicine in Ontario. The OAP represents the interests of patients, the public, and pathologists by fostering the highest standards in cancer diagnosis, laboratory testing, and forensic pathology. With approximately three hundred members, the OAP plays a key role in advocating for pathologists within agencies such as Cancer Care Ontario and the Ontario Breast Assessment Collaborative Group.

In addition, the association actively engages with the Ministry of Community Safety and Correctional Services of Ontario on forensic autopsies and related forensic medicine matters. The OAP is dedicated to advancing the field through the development of essential planning documents for government and healthcare administrators. It also supports collaboration between professionals and healthcare organizations through its Path2Quality initiative, which is highly regarded by the Ministry of Health and Long Term Care.

As a not-for-profit medical society, the OAP strives to enhance the quality and accessibility of pathology services, promote research, and maintain a high standard of knowledge and ethics among its members