A guiding system (1, 101) for guiding the insertion of a needle (2) and a catheter (6) for medical use in a biological tissue, the guiding system (1, 101) comprising: —the needle (2) —the catheter (6) inserted into the needle (2); —an optical fiber (8) provided with at least one optical sensor (10) and inserted into the catheter (6), —a first blocking device (12, 112) for firmly blocking the catheter (6) inside the needle (2).