In our days legal persons in general, and commercial partnerships and companies, in particular, participate in different relationships, being considerated by the most part of experts in company and civil law as the most active participants in civil and commercial circuit. Being artificial subjects of law, legal persons and commercial partnerships and companies are represented in relationships with third parties by their managers. The main purpose of this article is to analyze the relationships which appear between commercial partnerships and companies and their managers, on the one hand, and those ones between the managers an third parties, on the other one. In the same time, the analyze is structured as follows : general considerations about managers, legal nature and the content of the manager’s attributions, the particularities of representing commercial partnerships and companies (General Partnership, Limited Partnership, Limited Liability Company, Joint-Stock Company), the liability of managers, the representation office of commercial partnerships and companies.