Proper diagnosis is essential for effective treatment, yet in Canada health conditions are commonly underdiagnosed at all levels of the health system, meaning that they go undiagnosed or are diagnosed only after a delay. Underdiagnosis leads to inadequate treatment and potentially insufficient recovery and rehabilitation, as well as costly inefficiencies, such as repeat medical visits. Moreover, disparities in underdiagnosis in which vulnerable groups, such as women and Indigenous persons, are properly diagnosed at lower rates worsen existing inequities, which threatens the overall health of the general population. As health leaders and policy-makers seek to strengthen Canada's strained healthcare system, it will be important to address underdiagnosis and its causes, including systematic bias. Providing timely and accurate diagnoses for all patients is an essential component of delivering high quality, efficient, ethical, and cost-effective healthcare. The Canadian College of Health Leaders' Code of Ethics offers a framework for addressing underdiagnosis equitably. Utilizing the framework, suggestions are made for actions that can be taken at all levels of the health system to reduce underdiagnosis.