An arrangement for connecting a syringe to an electromechanical pump for drug infusion is provided. The syringe comprises a syringe body having a first end for discharging a drug and a second end connected to the pump in a removable manner. An axially sliding plunger is housed in the syringe body for causing suction and injection of the drug through the first end. The pump comprises a pump body having a sliding rod that causes sliding of the plunger within the syringe body. The pump body has a collar axially extending around the sliding rod and provided with engaging elements. The syringe body has engaging elements arranged to cooperate with the engaging elements of the collar for firmly connecting the syringe to the pump. An annular flange extends radially around the syringe body. The flange cooperates with the collar to establish a tight sealing between the syringe body and the collar.