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 first housing with a tip end of the at least one infusion needle arranged for penetrating the outer wall of the at least one first housing in at least one penetration area to allow for injecting a substance through said at least one penetration area via the at least one infusion needle, the at least one first housing being adapted for implantation inside the patient's body, and - at least one second housing connected to the first housing, wherein the at least one second housing having a remote location within the patient's body to the at least one infusion needle and first housing, the second housing is adapted for implantation inside the patient's body, - at least one reservoir adapted (R1, R2) for implantation inside the patient's body in the second housing, further adapted to be 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, - at least one drive unit adapted for implantation inside the patient's body with at least part of the drive unit placed in at least one of the first and second housing, 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 pump adapted for implantation inside the patient's body, to advance the substance from the reservoir to the at least one infusion needle, characterized in that: the pump is placed in at least one of the first and second housing, and in that the infusion needle is guided in a sheath between the first and second housing. - at least one infusion needle disposed at least partly within at least one first housing with a tip end of the at least one infusion needle arranged for penetrating the outer wall of the at least one first housing in at least one penetration area to allow for injecting a substance through said at least one penetration area via the at least one infusion needle, the at least one first housing being adapted for implantation inside the patient's body, and - at least one second housing connected to the first housing, wherein the at least one second housing having a remote location within the patient's body to the at least one infusion needle and first housing, the second housing is adapted for implantation inside the patient's body, - at least one reservoir adapted (R1, R2) for implantation inside the patient's body in the second housing, further adapted to be 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, - at least one drive unit adapted for implantation inside the patient's body with at least part of the drive unit placed in at least one of the first and second housing, 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 pump adapted for implantation inside the patient's body, to advance the substance from the reservoir to the at least one infusion needle, characterized in that: the pump is placed in at least one of the first and second housing, and in that the infusion needle is guided in a sheath between the first and second housing. the pump is placed in at least one of the first and second housing, and in that the infusion needle is guided in a sheath between the first and second housing.