Recent studies have found positive effects from hospital focus on both quality and cost. Some studies indicate that certain patient segments benefit from focus, while others have worse outcomes in focused hospital departments. The aim of this study was to establish the relationship between hospital focus and performance in elective surgery. We studied obesity surgery procedures performed in Sweden in 2016 (5152 patients), using data from the Scandinavian Obesity Surgery Registry (SOReg) complemented by a survey of all clinics that performed obesity surgery. We examined focus at two levels of the organization: hospital level and department level. We hypothesized that higher proportions of obesity surgery patients in the hospital, and higher proportions of obesity surgery procedures in the department, would be associated with better performance. These hypotheses were tested using multilevel regression analysis, while controlling for patient characteristics and procedural volume. We found that focus was associated with improved outcomes in terms of reduced complications and shorter procedure times. These positive relationships were present at both hospital and department level, but the effect was larger at the department level. The findings imply that focus is a viable strategy to improve quality and reduce costs for patients undergoing elective surgery. For these patients, general hospitals should consider implementing organizationally separate units for patients undergoing elective surgery.