Abstract: A modular multi-passage rotary coupling for transferring fluids in which pipes are rigidly connected with the inner fixed rings of the relevant modules by sleeves. The sleeves, after being coaxially butt-fastened at their bottom end with the pipes, enter proper bores specifically provided in the relevant fixed rings, inside which each of them is fastened under pressure by means of a closure and tight-sealing screw-threaded cap which is screwed down on a corresponding inner threading provided at the upper end of the relevant sleeve and urging, with the crown of its head, against the upper edge of the bore and also by a shoulder step jutting out at the bottom end of the sleeve and cooperating with the lower edge of the bore of the fixed ring.