A variety of local and systemic complications can occur during the administration of local anesthesia (LA). Diplopia is one of the very rare complications that follow a posterior superior alveolar (PSA) nerve block. This article describes a very rare case report and the possible mechanisms are discussed in detail. Diplopia is defined as double vision. The patient was administered PSA nerve block for the extraction of the upper right third molar tooth. After the extraction, the patient complained of double vision and not being able to gaze laterally with the right eye. The patient recovered completely after the anesthetic effect. Local and systemic complications do occur during and after administration of local anesthesia. The clinician needs to be aware of the complications and management.