An at least partly implantable system for injecting a substance into a patient's body, comprising - at least one infusion needle disposed at least partly within at least one housing with a tip end of the at least one infusion needle arranged for penetrating the at least one housing's outer wall in at least one penetration area, the at least one housing being adapted for implantation inside the patient's body, - at least one drive unit adapted for implantation inside the patient's body, the at least one drive unit being coupled to the at least one infusion needle and arranged at least for advancing and retracting the tip end of the at least one infusion needle so that the at least one infusion needle penetrates, upon advancement of the tip end or ends thereof, said at least one penetration area so as to allow for injecting the substance through said at least one penetration area via the at least one infusion needle, and - at least one reservoir (R 1, R 2) adapted for implantation inside the patient's body in fluid connection with the at least one infusion needle to supply to the infusion needle the substance to be injected into the patient's body, characterized in that the at least one drive unit comprises a mechanical drive element for transmitting kinetic energy from a remote location within the patient's body to the at least one infusion needle, wherein the mechanical drive element comprises at least one of; at least one wire and at least one rotating shaft, directly or indirectly cooperating with the infusion needle so as to cause movement of the needle upon actuation of at least one of: the at least one wire and the at least one rotating shaft, to cause the movement of the infusion needle. - at least one infusion needle disposed at least partly within at least one housing with a tip end of the at least one infusion needle arranged for penetrating the at least one housing's outer wall in at least one penetration area, the at least one housing being adapted for implantation inside the patient's body, - at least one drive unit adapted for implantation inside the patient's body, the at least one drive unit being coupled to the at least one infusion needle and arranged at least for advancing and retracting the tip end of the at least one infusion needle so that the at least one infusion needle penetrates, upon advancement of the tip end or ends thereof, said at least one penetration area so as to allow for injecting the substance through said at least one penetration area via the at least one infusion needle, and - at least one reservoir (R 1, R 2) adapted for implantation inside the patient's body in fluid connection with the at least one infusion needle to supply to the infusion needle the substance to be injected into the patient's body, characterized in that the at least one drive unit comprises a mechanical drive element for transmitting kinetic energy from a remote location within the patient's body to the at least one infusion needle, wherein the mechanical drive element comprises at least one of; at least one wire and at least one rotating shaft, directly or indirectly cooperating with the infusion needle so as to cause movement of the needle upon actuation of at least one of: the at least one wire and the at least one rotating shaft, to cause the movement of the infusion needle.