A one-way valve for medical infusion lines and the like, comprising a first tubular connector (2) and a second tubular connector (3), which define, respectively, an upstream passage (4) and a downstream passage (5) , which are coaxial and set transversely between which is a diaphragm (6) made of elastically deformable material co-operating in a fluid-tight way with an annular seat (14) to keep the valve normally closed. A filter (15 25 35), integrated in the valve, is axially clamped and blocked between the first tubular connector (2) and the diaphragm (.6) . (Figure 3)
