A vascular access device for haemodialysis permanently implantable in a patient having an arteriovenous fistula, the vascular access device being made of a biocompatible and sterilisable material, and comprising: - a relative first tubular element (2, 202) having a first and a second relative end (21, 221, 223), which are longitudinal, the first tubular element (2, 202) defining a first conduit which extends from the first to the second end (21, 221, 223); - a relative second tubular element (3, 303) having a first and a second relative end (31, 32, 231, 232) which are longitudinal, and defining a second conduit (33, 233) which extends from the relative first to the second end (31, 32, 231, 232); wherein the first end (31, 231) of the second tubular element (3, 303) is fixed to the first tubular element (2, 202) in an intermediate position between the first and the second end (21, 221, 223) of the first tubular element (2, 202), so that the second conduit (33, 233) is in fluid communication with the first conduit (22, 222) and so that the second end (32, 232) of the second tubular element (3, 303) is on a first side with respect to the first tubular element (2, 202); and - first fixing means comprising a first plurality of through-holes and being fixed to the first tubular element (2, 202) and/or second tubular element (3, 303) the first plurality of through-holes being arranged on the first side, with respect to the first tubular element (2, 202), and at the second end (32, 232) of the second tubular element (3, 303), wherein said vascular access device is conformed and dimensioned to be implantable in an arm of a patient having an arteriovenous fistula for haemodialysis with the first conduit (22, 222) interposed in series to the arteriovenous fistula, with respect to the blood flow therein, between a first portion and a second portion of the arteriovenous fistula, the first end (21, 221, 223) and the second end (21, 221, 223) of the first tubular element (2, 202) being fixed, respectively to the first portion and to the second portion of the arteriovenous fistula, at a relative end of the relative portion (51, 52) and the second end (32, 232) of the second tubular element (3, 303) and with the first plurality of through-holes arranged subcutaneously at an implant skin region in order to enable fixing of the first plurality of through-holes to the implant skin region by means of a first plurality of suture stitches, and a consequent fixing of the second end (32, 232) of the second conduit (33, 233) to the implant skin region. - a relative first tubular element (2, 202) having a first and a second relative end (21, 221, 223), which are longitudinal, the first tubular element (2, 202) defining a first conduit which extends from the first to the second end (21, 221, 223); - a relative second tubular element (3, 303) having a first and a second relative end (31, 32, 231, 232) which are longitudinal, and defining a second conduit (33, 233) which extends from the relative first to the second end (31, 32, 231, 232); wherein the first end (31, 231) of the second tubular element (3, 303) is fixed to the first tubular element (2, 202) in an intermediate position between the first and the second end (21, 221, 223) of the first tubular element (2, 202), so that the second conduit (33, 233) is in fluid communication with the first conduit (22, 222) and so that the second end (32, 232) of the second tubular element (3, 303) is on a first side with respect to the first tubular element (2, 202); and - first fixing means comprising a first plurality of through-holes and being fixed to the first tubular element (2, 202) and/or second tubular element (3, 303) the first plurality of through-holes being arranged on the first side, with respect to the first tubular element (2, 202), and at the second end (32, 232) of the second tubular element (3, 303), wherein said vascular access device is conformed and dimensioned to be implantable in an arm of a patient having an arteriovenous fistula for haemodialysis with the first conduit (22, 222) interposed in series to the arteriovenous fistula, with respect to the blood flow therein, between a first portion and a second portion of the arteriovenous fistula, the first end (21, 221, 223) and the second end (21, 221, 223) of the first tubular element (2, 202) being fixed, respectively to the first portion and to the second portion of the arteriovenous fistula, at a relative end of the relative portion (51, 52) and the second end (32, 232) of the second tubular element (3, 303) and with the first plurality of through-holes arranged subcutaneously at an implant skin region in order to enable fixing of the first plurality of through-holes to the implant skin region by means of a first plurality of suture stitches, and a consequent fixing of the second end (32, 232) of the second conduit (33, 233) to the implant skin region.