For several years, the issue of informality, non-compliance with current laws, and its impact on productivity or performance has occupied a central place in writings on informal entrepreneurship, both in the media and in research studies. In the health sector, where informal microenterprises play a crucial role, this issue takes on a particular dimension. While performance remains a major concern for these enterprises, they are gradually integrating the need to formalize their activities, both to mitigate the negative effects of informality and to enhance their capacity for productivity and performance. This repositioning appears to be gradually achievable, not only without creating significant opposition between these two goals but also by fostering an understanding of their mutual influences. This study seeks to address the effects of informality on the performance of informal health micro-units while providing an overview of the state of the art in this field. Research conducted on the link between informality and performance has shown that formalizing informal health micro-units enhances their performance and, consequently, their contribution to economic growth.