Percutaneous aspirational biopsy of intrathoracic lesions has become a popular technique. One of the rarest complications is that of implantation of malignant cells within the needle tract and subsequent development of a chest wall mass. A case of chest wall implantation of adenocarcinoma of the lung after thin-needle biopsy is reported. The lesion was successfully treated with radical full-thickness excision of the chest wall and immediate reconstruction with a large rectus abdominis musculocutaneous flap.