This literature marketed report as received from a physician refers to a 25 years old, right hand-dominant female patient with a presumptive diagnosis of left carpal tunnel syndrome of 5 months duration. The patient's chief complaint was loss of hand dexterity due to the inability to flex her left thumb interphalangeal joint. The patient had received two of the series of three GARDASIL vaccination into the left deltoid of the affected upper extremity. Three days after the second injection, she noted intense burning pain in her entire left upper arm. After the pain subsided over the next 24 to 48 hours, the patient noted that she was unable to grip a glass due to lack of thumb flexion while washing dishes. Other than the initial pain, she denied febrile illness, night sweats, chills, or any dermatologic-type rash. At the time of second injection, patient denied having viral or flu-like symptoms. There was no neurological symptoms, numbness, tingling, or paresthesias at the time of injection to suggest an intraneural injury. Initial electromyographic(EMG) and nerve conduction velocity studies performed 3 months after the onset of symptoms were intrepreted as normal; however, electro-diagnostic motor testing of the flexor pollicis longus(FPL), pronator quadratus, and flexor digitorum profundus(FDP) to the index finger was not performed. Serologic testing for rheumatoid and other autoimmune or inflammatory disorders was normal. She denied hereditary familial neuritis or neuralgic amyotrophy. On physical examination, patient had full active and passive range of motion of her cervical spine, shoulder, elbow, forearm and wrist. Left thumb IP joint active range of motion was absent with passive range of motion from 0 degrees to 60 degrees. She did demonstrate active flexion against gravity with her index finger FDP; however, she was unable to flex it against minimal resistance, indicating grade 3/5 motor strength. Grip strength measured 55lb on the right and 45 lb on the left. Sensation was intact and symmetric with Semmes-Weinstein monofilament testing and 128Hz vibratory sensation. Tinel's sighs were negative over the brachial plexus. Guyon's canal, carpal tunnel, and dorsal radial sensory nerve. Repeat EMG and nerve conduction velocity studies performed 5 months after the inciting event. This study demonstrated increased insertional activity in the AIN innervated FPL and index finger FDP as well as the median nerve innervated palmaris longus and abductor pollicis brevis. This study was consistent with a high median nerve distribution palsy. Physician recommended treatment by observation. By 8 months, the patient began to experience increasing strength in her index finger FDP. At 1 year after the onset of symptoms, she had largely regained her index FDP strength but still had complete loss of function of her FPL muscle with a persistent loss of manual dexterity. Fortunately, at 16 months following the initial insult, patient experienced return of FRL function with improved dexterity, obviating the need for tendon transfer. Reports of brachial plexus neuritis can be found in the literature after other vaccinations. Brachial neuritis after vaccination administration is a well-described phenomenon although the exact etiology is unknown. Cases of neuritis after tetanus vaccination, an immune-mediated, local demyelinating response to the tetanus toxoid is believed to be the cause of the neuritis. The CDC considers brachial neuritis occurring 2 to 28 days after tetanus vaccination a reportable event with presumed vaccine causation; however, this relationship has not been defined for brachial neuritis after HPV vaccination. The HPV vaccine, however, does not contain a toxoid so the exact mechanism leading to neuritis of the brachial plexus remains unclear. To our knowledge, this is the second case of brachial neuritis after an HPV vaccine reported in the literature. In our search of the Vaccine Adverse Event Reporting System (VAERS) data of reportable events, 17 cases of the HPV vaccine causing side effects listed as "brachial plexus injury," "brachial plexopathy," and "brachial radiculitis" were identified, including 16 from GARDASIL and 1 from CERVARIX. Approximately 30,000 VAERS reports are filed annually, with l 0- 15% classified as serious; however, limited clinical information is available using this database. Additional information has been requested.