Y-connector for medical lines

A Y-connector in medical lines used for introducing a secondary flow into the flow of a primary liquid. Y-connector for medical lines, comprising a tubular body (1) provided with a first inlet (2) coaxial to the tubular body (1) and containing a valve device formed by an elastic element (6) sealingly closing said first inlet in an openable manner, an outlet, and a second inlet (4) arranged obliquely to the tubular body (1) and communicating therewith between the first inlet (2) and the outlet (3). The tubular body (1) is formed with an inner septum (10) for deviating the flow coming from the second inlet (4) towards the hollow elastic element (6) prior to directing it to the outlet (3). The inner septum extending axially and being provided with a radial end portion connected to the tubular body in proximity of said second inlet so as to define a first chamber open towards the elastic element and closed on a side of the outlet, and a second chamber open towards the elastic element and towards the outlet wherein said inner septum is offset relative to an axis of the tubular body such that the first chamber has a radial size greater than that of the second chamber. The smaller radial size of the second chamber creates - in use - an advantageous effect on the dynamics of the liquid flow in the cavity of the elastic hollow element, in the area for introducing the liquid from the first inlet where greater stagnation could occur.