Popliteal block is a widely used to provide anesthesia or analgesia for below-knee surgical procedures. Aim of work: It is a comparison between posterior and lateral approaches for US-guided popliteal block to find out the approach with the best outcome. Patients and methods: In this randomized, double-blind study, eighty ASA physical status of class I and II patients undergoing below knee surgery were involved. These patients were randomly allocated according to the used approach for US-guided popliteal block into to two equal groups: posterior and lateral approaches groups. In this study, number of attempts to get the proper injection site, block performance time, success rate, the characters of the produced anesthesia (onset, potency and duration), need to supplementary saphenous nerve block, postoperative rescue analgesia, discomfort rate in respect to position and needle insertion and the associated complications were recorded. Results: Mean block performance time was significantly longer with posterior than with lateral approach. Number of attempts to get the proper injection site, success rate, characters of the produced anesthesia, postoperative rescue analgesia were comparable in both approaches. Discomfort rate in respect to position was higher in posterior approach and discomfort rate and severity in respect to needle insertion were higher in lateral approach. The associated complications were not detected in both approaches. Conclusions: Although the characters of the produced anesthesia by US-guided popliteal block via posterior and lateral approaches were comparable, however the lateral approach has shorter performance time and associated with less position related patients’ discomfort.