An increasing number of countries are introducing new health professions, such as Nurse Practitioners (NPs) and Physician Assistants (PAs). There is however limited evidence, on whether these new professions are included in countries' workforce planning.A cross-country comparison of workforce planning methods. Countries with NPs and/or PAs were identified, workforce planning projections reviewed and differences in outcomes were analysed, based on a review of workforce planning models and a scoping review. Data on multi-professional (physicians/NPs/PAs) vs. physician-only models were extracted and compared descriptively. Analysis of policy implications was based on policy documents and grey literature.Of eight countries with NPs/PAs, three (Canada, the Netherlands, United States) included these professions in their workforce planning. In Canada, NPs were partially included in Ontario's needs-based projection, yet only as one parameter to enhance efficiency. In the United States and the Netherlands, NPs/PAs were covered as one of several scenarios. Compared with physician-only models, multi-professional models resulted in lower physician manpower projections, primarily in primary care. A weakness of the multi-professional models was the accuracy of data on substitution. Impacts on policy were limited, except for the Netherlands.Few countries have integrated NPs/PAs into workforce planning. Yet, those with multi-professional models reveal considerable differences in projected workforce outcomes. Countries should develop several scenarios with and without NPs/PAs to inform policy.