Abstract: The present invention relates to a transducer protector 20 designed to be used in an extra-corporeal circuit 22. It comprises a first half-shell 24, a second half-shell 34 and a hydrophobic semi-permeable membrane 38 enclosed between the two half-shells 24 and 34. The first half-shell 24 comprises a first tubular connector 26 in turn comprising a seat 28 having a substantially cylindrical shape and defining an axis X. The second half-shell 34 comprises a second tubular connector 36 designed for connection to a transducer 21. The seat 28 is designed to receive an end 42 of a branch pipe 40 from the extra-corporeal circuit 22. The end 42 defines a front surface substantially in the form of an annulus 44 and can be inserted inside the seat 28 in the axial direction along the axis X. The seat 28 comprises one more abutments 30 designed to form a support for the front surface of the end 42 so as to define a limit stop in the axial direction for the end 42.