A system for implementing a modular structure having two or more cot places, characterised in that the modular structure is implemented by the mutual interconnection of single units (1) made of a pair of posts (2) and of at least one crosspiece (3) assembled in a sandwich arrangement blocked in position by fastening means (4). The system has the main advantage of providing a variable structural modularity to assume a plurality of different conditions, both with regard to the combinability thereof in terms of number of cot places and with regard to the overall dimensions thereof, while maintaining the same number of cot places, according to the varying of the user's needs over time.