CONTEXT Health workforce cross-border mobility has an impact not only on individual health workers, but also on how health services are organized, planned, and delivered. This paper presents the results of a study of current mobility trends of health professionals along the borders between Portugal and Spain. The objective was to describe the profile of mobile physicians and nurses; to elicit the opinions of employers on mobility factors; to describe incentive policies to retain or attract health professionals; and to collect and analyse employers' opinions on the impact of this mobility on their health services. METHODS Phone interviews of key informants were used to collect relevant data. The interviews were conducted during December 2010 and January 2011 in health organizations along the border of the two countries. In Portugal and Spain, four and 13 organizations were selected, respectively. Interviews were obtained in all the Portuguese organizations and in four of the Spanish organizations. RESULTS Findings suggest that cross-border mobility between the two countries has decreased. From Spain to Portugal, mobility trends are mainly of physicians who seek professional development in the form of specialization, the availability of positions, better salaries, and the perceived good living conditions. The mobility of nurses lasted until 2008, when reforms improved working conditions in Spain and contributed to reversing the flow. Since then, there has been an increase of Portuguese nurses going to Spain seeking better working conditions or simply a job. Portuguese nurses as well as Spanish physicians are well considered in terms of professionalism and qualifications by their Spanish and Portuguese hosts, respectively. CONCLUSIONS There is a deficit of valid data on the health workforce in general. The present study allowed further exploration of the reality of the mobility trends between Portugal and Spain. At present, the mobility trends are mainly of Spanish physicians to Portugal and Portuguese nurses to Spain. There is a consensus on both sides of the border that the benefits of migratory flows are much greater than the limited problems (for example, language and salary differences) that they may bring.