Abstract: For cleaning the tubes (1) of a heat exchanger (2) through which flows a fluid between an upstream duct (3) and a downstream duct (4), by means of cleaning bodies (5), recourse is had to a sealed box (6) provided with four apertures (J,K,L,M) connected externally so as to define respectively a section (J,K) of the upstream duct and a section (L,M) of the downstream duct, a rotary support (7) mounted in this box and dividing it into two diametrically opposite compartments, two identical baskets (8,9) permeable to the fluid but not to the cleaning bodies and mounted in the two compartments so as to be open solely in the direction of the exchanger, and means (10) for rotating the support by half a revolution so as to switch over the two baskets and their functions (supply of cleaning bodies and collection of same).