A catheter insertion device comprises: a housing (12, 122) having a base (14, 124); a catheter (28, 130) movable between a first retracted position and a second extended position with respect to said base (14, 124); an insertion needle (30, 142) within said catheter and movable between a first retracted position and a second extended position with respect to said base and catheter; a spring (90, 152) disposed in said housing, characterised in that the catheter insertion device further comprises: a movable spring retainer (92, 154) having a first end configured for engaging said base and a second end engaging said spring for releasably retaining said spring in a compressed state; and a movable actuator (26, 126) for actuating said device, said catheter and needle being coupled to said actuator and being movable between a first position where said catheter and needle are retracted with respect to said actuator, and a second position where said catheter and needle extend from said base, and where said spring retainer releases said spring when said actuator is moved to said second position, where said first end of said movable spring retainer contacts said base to release said second end of said spring retainer from said spring and automatically retract said insertion needle. a housing (12, 122) having a base (14, 124); a catheter (28, 130) movable between a first retracted position and a second extended position with respect to said base (14, 124); an insertion needle (30, 142) within said catheter and movable between a first retracted position and a second extended position with respect to said base and catheter; a spring (90, 152) disposed in said housing, characterised in that the catheter insertion device further comprises: a movable spring retainer (92, 154) having a first end configured for engaging said base and a second end engaging said spring for releasably retaining said spring in a compressed state; and a movable actuator (26, 126) for actuating said device, said catheter and needle being coupled to said actuator and being movable between a first position where said catheter and needle are retracted with respect to said actuator, and a second position where said catheter and needle extend from said base, and where said spring retainer releases said spring when said actuator is moved to said second position, where said first end of said movable spring retainer contacts said base to release said second end of said spring retainer from said spring and automatically retract said insertion needle. a movable spring retainer (92, 154) having a first end configured for engaging said base and a second end engaging said spring for releasably retaining said spring in a compressed state; and a movable actuator (26, 126) for actuating said device, said catheter and needle being coupled to said actuator and being movable between a first position where said catheter and needle are retracted with respect to said actuator, and a second position where said catheter and needle extend from said base, and where said spring retainer releases said spring when said actuator is moved to said second position, where said first end of said movable spring retainer contacts said base to release said second end of said spring retainer from said spring and automatically retract said insertion needle.