This is the first case report describing the epidural misplacement of an infusion catheter, which was intended to be located in the thoracic paravertebral space using an ultrasound-guided technique. The patient was a 57-year-old female undergoing a laparoscopy-assisted left partial nephrectomy. Before surgery, a Tuohy needle was inserted into the paravertebral space at the left ninth intercostal space using an in-plane transverse ultrasound-guided approach in the lateral-to-medial direction. A catheter was then threaded into the paravertebral space through the needle. Subsequently, the catheter position was secured, although ultrasound-guided confirmation of air injected through the catheter into the paravertebral space was not obtained. Twenty milliliters of 0.5 % levobupivacaine was administered through the catheter at both the initiation and conclusion of surgery. A neurologic examination following surgery revealed paraplegia, along with sensory deficits in the bilateral T3-S5 dermatome. The motor dysfunction in the lower extremities lasted 7 h, and the sensory block lasted 13.5 h. Postoperative radiologic confirmation of the catheter position concomitant with the spread of radiopaque dye revealed that the tip of the catheter was lying in the epidural space. Unless precise attention is paid to detection of the catheter tip location, a thoracic paravertebral catheter can enter into the epidural space even under ultrasound guidance.