Selective transforaminal periradicular infiltration with local corticosteroids and anesthetics has been performed for preoperative evaluation of lumbosacral pain and for patients with sciatia. From July 2001 to November 2003, 143 patients with unilateral sciatica were treated with computed tomography (CT)-guided transforaminal periradicular infiltration. Needle puncture was possible without difficulty in all patients. Of all 143 infiltrations, 140 were followed up with the recovery of leg and back pain and improvement of the straight leg-raising test (SLRT). Minor complications were seen, but major complications and mortality did not occur in our series. In summary, CT guidance allows safe and precise needle positioning, and it can readily demonstrate the spread of the medications in the exact periradicular space.