Disclosed is a one-way, check or non-return valve for medical infusion lines with axially clamped filter element with annular valve seat to provide a more secure placement of the filter. The valve comprises a body having a first tubular connector and a second tubular connector. The first tubular connector and second tubular connector define, respectively, an upstream passage and a downstream passage coaxial with each other. Set transversely between them is a diaphragm made of elastically deformable material co-operating in a fluid-tight way with an annular valve seat to keep the valve normally closed. A predetermined pressure of fluid in the upstream passage brings about a displacement or an elastic deformation of the diaphragm and consequent opening of the valve. The valve is provided with a filter integrated within the body and including a permeable membrane carried by an annular element and set between the first tubular connector and the diaphragm. The annular element is axially clamped and blocked between the first and second tubular connectors and is formed with the annular valve seat.
