The invention relates to a syringe with a retractable needle comprising a barrel (2) having a nozzle (19) integrated in a male Luer adapter element (26); a piston (3) slidably arranged in the barrel (2) and coupled to a sealing element (16), said sealing element (16) having a central channel (20); a needle assembly comprising a needle (4), a needle holder (6) and a female Luer adapter element (7); a spring assembly arranged in the piston (3) comprising a spring sleeve (12), a spring (13) mounted on the spring sleeve (12), a spring tensioning element (14) located on the spring sleeve (12) and held in position by the piston wall, and a plunger (15) mounted within the spring sleeve; and a piston cap (10); said piston (3) being coupled to the sealing element (16) by means of the spring tensioning element (14); said spring sleeve (12) being held in position within the piston (3) by a ring element (18) protruding from the inner wall of the piston (3) and supporting the proximal end of the spring sleeve (12), the spring sleeve extending into the channel (20) of the sealing element (16) to the distal end thereof; said spring sleeve (12) comprising at its distal end a circular protrusion (21) on the inside designed to engage a circular recess (22) at the proximal end of the needle holder (6); wherein the piston (3) comprises a holding ring (11) on its inner surface designed to engage with an outer flange (17) of the spring sleeve (12) after actuation of the spring (13).