Abstract: A suction injector, particularly for use with hypodermic injections, has a liquid container with a compartment containing pressurized gas, a hose to a cannula into a suction cup, which may be replaced after every use, consisting of an outer chamber with stored underpressure, which works, after a hole is opened by the shifting of supporting tube, moved by the pressure of skin pushing against this supporting tube. The underpressure of the suction cup starts a kind of spring driven roller pump provided with blocking dosing pegs for a multiple dosing choise. A valve for automatic reventilation is provided, as is a blocking and marking mechanism, relating to the emptying of the liquid supply, consisting of a taster finger, engaged in a hose loop, which frees the movement of a spring driven seivel arm against the skin and the suction cup, if the medicine supply is emptied. A revolution counter for the control of therapy is provided.