Low profitability has been responsible for the insolvency of a large number of health plan operators (HPO) in recent years, which increasingly requires these entities to assess which services can be optimized without compromising their final activities. An answer to this problem may lie in the adequate dimensioning of support activities. Therefore, the aim of this study is to investigate the economies of scale in the support activities of Brazilian HPO. In the presence of such economies, it can be considered that operators have room to dilute their administrative expenses, suggesting that profitability can be increased without the need for large price increases, which can guarantee the survival of companies in the sector without penalizing their customers. For this purpose, panel data regressions with Random Effects (RE), Fixed Effects (FE) and pooled were estimated, considering 5,185 observations for the period 2011 – 2018. The results found by estimating the total cost function were favorable to the hypothesis of economies of scale in the supplementary health sector. Finally, it was also possible to verify that the type of operator and the geographic location of the administrative headquarters of these entities contribute to the scale effect to a greater or lesser extent. These results show that the economies of scale existing in the sector can significantly contribute to the operational and financial maintenance of various HPO, providing an alternative to mitigate the low profitability of these companies.