A 67-year-old woman was admitted to our hospital for a complete medical evaluation of a pulmonary nodule on a chest X-ray film, which was found during an annual check-up. A loud bruit was audible over the left chest and the supraclavicular region. Computerized tomography (CT) scan and magnetic resonance imaging revealed an arteriovenous fistula from a branch of the left subclavian artery into the paravertebral veins. Angiography disclosed that the arteriovenous fistula was fed by the left costocervical artery. Transarterial embolization of the arteriovenous fistula was done with 5 mechanical detachable coils and 2 micro coils. Postembolization angiography showed a marked decrease in blood flow and near-elimination of the arteriovenous fistula. The shrinkage of the arteriovenous fistula was also observed on CT scan. This patient had been in a traffic accident, and had been clinically well before the accident. Post-traumatic arteriovenous fistula was strongly suspected, because a pulmonary nodule on chest X-ray film and a bruit were found after a traffic accident.