The accuracy of four electronic apex locators (EALs) to locate the apical limit in teeth with simulated horizontal oblique root fractures was investigated. A horizontal oblique incomplete root fracture was simulated on 20 freshly extracted maxillary anterior teeth by means of a notch made on the vestibular root plane 8 mm from the anatomic apex. The EALs investigated were the ProPex (Dentsply Maillefer, Ballaigues, Switzerland), the NovApex (Forum Technologies, Rishon Le-Zion, Israel), the Root ZX (J. Morita Corp, Kyoto, Japan), and the Elements Apex Locator (SybronEndo, Orange CA). The electronic measurements were compared with the real "working length." The accuracy obtained was of 80% (n = 16) and 95% (n = 19) with the ProPex, 70% (n = 14) and 95% (n = 19) with the NovApex, 60% (n = 12) and 90% (n = 18) with the Root ZX, and 60% (n = 12) and 85% (n = 17) with the Elements Apex Locator when tolerances of 0.5-mm and 1.0-mm tolerance were, respectively, allowed. The analysis of variance (p > 0.05) and chi-square test (0.5 mm/p = 0.47 and 1.0 mm/p = 0.63 tolerances) showed no statistical significant differences between the EALs at either tolerance level.