A spring retainer (60) is provided for a syringe (10) that comprises a barrel (40), a plunger (20), a spring (90) and a retractable needle (50) that can couple with the plunger (20) for spring-driven retraction of the coupled needle (51) and plunger (20). The spring retainer (60) has first (70) and second (80) body members that co-operate to releasably maintain the spring (90) in a compressed state until the plunger (20) is coupled to the retractable needle (50) after depression of the plunger (20) to deliver the fluid contents of the syringe (10). Depression of the plunger (20) triggers rotational disengagement of the first (70) and second (80) body members to allow decompression of the spring (90) which forces retraction of the retractable needle (50) into the barrel (40). Rotational disengagement of the first (70) and second (80) body members also assists rotation of the plunger (20) into a final, inoperable position.