PURPOSE: To determine to what extent local anesthetic reduces postoperative pain after pediatric strabismus surgery. METHODS: In this double-masked, randomized clinical trial of 50 children 13-91 months of age undergoing strabismus surgery, subjects were randomly assigned to one of three treatments given at the conclusion of surgery: topical lidocaine gel and sub-Tenon's (balanced salt solution) placebo (n = 16), topical placebo (hypromellose) and sub-Tenon's bupivacaine 0.75% (n = 17), or topical and sub-Tenon's placebo (n = 17). Pain was otherwise managed systemically in the usual fashion by the masked anesthesia team and assessed at regular postoperative intervals by a masked observer using an objective, validated pain scale. RESULTS: Average pain in the first 30 minutes was 6.57, 6.36, and 6.58 in the lidocaine, bupivacaine, and placebo groups, respectively, and was significantly lower (P = 0.016) for bupivacaine vs placebo. The bupivacaine group had significantly lower scores for pain after 30 minutes, total pain, and peak pain versus the lidocaine group. CONCLUSIONS: Sub-Tenon's bupivacaine may reduce postoperative pain in children undergoing strabismus surgery.