A system for injecting a fluid medicament into a patient which comprises: an injector comprising first and second motors (250, 254) mounted therein; a hypodermic syringe (226,224) pre-filled with the fluid medicament, the hypodermic syringe comprising a syringe chamber for holding the fluid medicament therein, an injection needle extending from the syringe chamber, and a plunger slidably mounted for advancement into the syringe chamber to expel fluid medicament therefrom through the injection needle; a cassette for receiving and holding the hypodermic syringe, the cassette having a latch mechanism for holding the syringe in the cassette, wherein the first motor being engageable with the cassette for selectively latching and unlatching the syringe from the cassette and for movement of the unlatched syringe in the cassette, between a first position and a second position, when the cassette is mounted in the injector; and a controller for coordinated control of the first and second motors (250, 254); wherein the latched syringe is fixedly held in the first position in the cassette; wherein the first position is a proximal position for hiding the syringe needle inside the cassette, and the second position is a distal position where the needle extends from the cassette for injection of the medicament; and wherein a duty cycle requires, in sequence: controller control of the first motor for movement of the unlatched syringe at a predetermined speed from the first position to the second position; controller control of the second motor for advancement of the plunger into the syringe chamber at a predetermined rate for expelling fluid medicament from the syringe; and controller control of the first motor for withdrawal of the syringe from the second position to the first position and for activation of the latch to fixedly hold the syringe in the first position in the cassette. an injector comprising first and second motors (250, 254) mounted therein; a hypodermic syringe (226,224) pre-filled with the fluid medicament, the hypodermic syringe comprising a syringe chamber for holding the fluid medicament therein, an injection needle extending from the syringe chamber, and a plunger slidably mounted for advancement into the syringe chamber to expel fluid medicament therefrom through the injection needle; a cassette for receiving and holding the hypodermic syringe, the cassette having a latch mechanism for holding the syringe in the cassette, wherein the first motor being engageable with the cassette for selectively latching and unlatching the syringe from the cassette and for movement of the unlatched syringe in the cassette, between a first position and a second position, when the cassette is mounted in the injector; and a controller for coordinated control of the first and second motors (250, 254); wherein the latched syringe is fixedly held in the first position in the cassette; wherein the first position is a proximal position for hiding the syringe needle inside the cassette, and the second position is a distal position where the needle extends from the cassette for injection of the medicament; and wherein a duty cycle requires, in sequence: controller control of the first motor for movement of the unlatched syringe at a predetermined speed from the first position to the second position; controller control of the second motor for advancement of the plunger into the syringe chamber at a predetermined rate for expelling fluid medicament from the syringe; and controller control of the first motor for withdrawal of the syringe from the second position to the first position and for activation of the latch to fixedly hold the syringe in the first position in the cassette.