The purpose of this prospective, randomized, blinded study was to determine the effect of apical trephination on postoperative pain and swelling in symptomatic necrotic teeth. Fifty emergency patients participated, and each had a clinical diagnosis of a symptomatic necrotic tooth with associated periapical radiolucency. After endodontic treatment, patients randomly received either an apical trephination or mock trephination procedure. The trephination procedure used a Stabident perforator to provide an initial opening in the cortical bone that was enlarged with files (#25 through #120) and an endodontic spoon. Postoperatively, each patient received: ibuprofen; acetaminophen with codeine (30 mg); and a 7-day diary to record pain, percussion pain, swelling, and number and type of pain medication taken. Results demonstrated the use of an apical trephination procedure did not significantly (p > 0.05) reduce pain, percussion pain, swelling, or number of ibuprofen tablets taken in symptomatic necrotic teeth with periapical radiolucencies. The trephination procedure did significantly (p < 0.05) reduce the use of acetaminophen with codeine overall for the 7 days. In conclusion, because there was not a significant reduction in pain, percussion pain, or swelling we cannot recommend the routine use of an apical trephination procedure, as used in this study, in symptomatic necrotic teeth with radiolucencies.