Ultrasound is a novel method of nerve localization but its use for lower extremity blocks appears limited with only reports for femoral 3-in-1 blocks. We report a case series of popliteal sciatic nerve blocks using ultrasound guidance to illustrate the clinical usefulness of this technology.The sciatic nerve was localized in the popliteal fossa by ultrasound imaging in 10 patients using a 4- to 7-MHz probe and the Philips ATL HDI 5000 unit. Ultrasound imaging showed the sciatic nerve anatomy, the point at which it divides, and the spatial relationship between the peroneal and tibial nerves distally. Needle contact with the nerve(s) was further confirmed with nerve stimulation. Circumferential local anesthetic spread within the fascial sheath after injection appears to correlate with rapid onset and completeness of sciatic nerve block.Our preliminary experience suggests that ultrasound localization of the sciatic nerve in the popliteal fossa is a simple and reliable procedure. It helps guide block needle placement and assess local anesthetic spread pattern at the time of injection.