Purpose: To document the contamination rate of sutures used in strabismus surgery and evaluate the reduction of contamination using antibiotic-coated and antiseptic/antibiotic-coated sutures. Methods: This was a prospective randomized analysis of suture contamination and potential prophylaxis measures after strabismus surgery. Muscle sutures (6-0 polyglactin) used in 302 consecutive cases of strabismus from October 2008 to May 2009 were collected and randomly assigned to three groups: (1) a control without pretreatment sutures (61); (2) antibiotic/steroid-coated sutures (200); and (3) antiseptic-soaked and antibiotic/steroid-coated sutures (141). The sutures were used under sterile conditions and then cut into pieces and transferred to blood agar plates, which were incubated for 48 hours and then checked for growth. Results: Group 1 had bacterial growth in 17 of 61 (28%) sutures; group 2 had growth in 44 of 200 (22%) sutures; and group 3 had growth in 12 of 141 (9%) sutures. The reduction in bacterial growth using the antibiotic/antiseptic coating was significant ( P = .006). One patient developed coagulase-negative Staphylococcus epidermidis endophthalmitis 1 week after surgery, which was promptly diagnosed and successfully treated. No complications from the antibiotic-coated or antiseptic-soaked sutures were noted. Conclusions: Although endophthalmitis after strabismus surgery is rare, estimated at 1 in 35,000 to 1 in 185,000, visual outcome is uniformly poor. The authors hypothesize that strabismus sutures can be contaminated via contact with the eyelashes and skin, providing a possible conduit for endophthalmitis. Bacterial contamination of strabismus sutures is high (28%) and can be reduced significantly if sutures are soaked in antiseptic before use.