Background: Work ability (WA) is an indication of how well someone's health, skills and experience match current job demands. The aim of this study was to ascertain whether the work ability model can provide a useful explanatory framework to understand some elements of sustainable employability (SE) amongst GPs. Methods: A thematic analysis of 19 in-depth interviews with GPs in the Northern Rivers region of NSW, Australia, was conducted and formed the basis for a qualitative validation of the work ability model. Results: In order to provide a more comprehensive reflection on the factors and dynamics found to underpin work ability amongst ageing GPs required the creation of specific subcategories within the WA model. Additionally, new themes relevant to general practice also emerged from the data. The analyses revealed a set of important, new factors and relationships that required additions and refinements to the original model, in order to fully explain sustainable employability in this GP sample. These new emerging themes that required model extension were 'Work-life balance and lifestyle', 'Extended social community' and 'Impact of gender'. Conclusion: While the WA model provides a basic explanatory framework for understanding some elements of sustainable employability amongst GPs, a revision of the current model has been proposed to sufficiently describe the factors impinging on sustainable employability in this group. The extended model can potentially be used for addressing workforce planning issues and to assist in programme design to promote sustainable employability amongst GPs and could potentially be translated to other health professional groups.