The article aims to analyze physicians' commuting from a new perspective, verifying their movement and work supply between health regions, specifically in five regions in the state of São Paulo, Brazil. This movement was referred to as physicians' commuting, defined as the diversity of job situations over the course of a given time period in given geographic territories. The methodology used was a multiple case study with quantitative and qualitative approaches. All the physicians registered in the National Registry of Healthcare Establishment (CNES) in March 2015 were categorized as either "exclusive physicians", with employment contracts exclusively in the target health region or "non-exclusive physicians", with employment contracts both in that region and in other regions. We analyzed the region's socioeconomic and health characteristics and healthcare structure. The region's dependence on external physicians, namely those residing in other regions, varied from 30 to 40%; dependence was higher in the more economically developed regions and less in the less developed regions. Internal dependence, among municipalities, was close to 40% in the regions with higher economic development and reached 60% in the less developed regions. Non-exclusive physicians tended to be more specialized, working more in surgical and diagnostic specialties, while exclusive physicians worked more in basic and clinical specialties, suggesting that the commuting patterns are associated with the organization of different arrangements of healthcare provision. We identified a growing share of outsourced arrangements and the importance of regionally negotiated actions. Such studies can better orient more integrated redistributive policies.