Projections are considered a useful tool in the planning of human resources for health. In Mexico, the supply and demand of specialist doctors are clearly disconnected, and decisions must be made to reduce labour market imbalances. Thus, it is critical to produce reliable projections to assess future interactions between supply and demand. Using a service demand approach, projections of the number of specialist physicians required by the three main public institutions were calculated using the following variables: a) recent recruitment of specialists, b) physician productivity and c) retirement rates. Two types of scenarios were produced: an inertial one with no changes made to current production levels and an alternative scenario adjusted by recommended productivity levels. Results show that institutions must address productivity as a major policy element to act upon in future contracting of specialist physicians. The projections that adjusted for productivity suggest that the hiring trends for surgeons and internists should be maintained or increased to compensate for the increase in demand for services. In contrast, due to the decline in demand for obstetric and paediatric services, the hiring of new obstetrician-gynaecologists and paediatricians should be reduced to align with future demand.