The basis for doctoral thesis is the co-ownership as it is in the current legislation. It is focused on a detailed analysis of the main content of co-ownership, deficiencies in the legislation, comparison of the current legislation with the proposed legislation of the new Civil code (or how are the deficiencies solved). It also analysis legal relations within the co-ownership, history of the co-ownership and also comparison of co-ownership with common assets of spouses as related legal institutes or housing ownership, or legal regulation of co-ownership in legislation abroad. There are defined different aspects of co-ownership: its origin, content, end and protection. There are given examples of court decision in Czech Republic regarding some partial areas of the issue.