Inadvertent perforation of the sclera is a widely recognized complication of eye muscle surgery. In the 1960s and 1970s, it was estimated to occur in 9% to 12% of patients operated. Fortunately, dreaded vision-threatening sequelae have been much less common. To better define the occurrence and sequelae of this complication, we sent a questionnaire to all 342 members of the American Association for Pediatric Ophthalmology and Strabismus. Scleral perforations, defined to include known retinal damage, occurred in 728 of nearly 554,000 eye muscle procedures performed by 223 surgeons. Perforations were two times more common with residents or fellows operating. They occurred not only during muscle reattachment (633 cases), but also during muscle disinsertion (24 cases), muscle dissection (6 cases), passage of traction sutures beneath the lateral rectus (5 cases), and preplacement of muscle sutures (5 cases). Many other perforations may have been unrecognized and uncounted. Visual loss was uncommon, occurring in only nine patients. Fourteen retinal detachments included four cases with partial and two with total loss of vision. Only three cases of endophthalmitis occurred, one resulting in partial visual loss and two in total visual loss. Techniques suggested by respondent surgeons to avoid perforations are discussed.