Although regional anaesthesia has become safer, there are an increasing number of articles regarding complications of regional blocks. During the last few years, many authors have suggested the use of ultrasound to minimize the appearance of complications. This review was performed, through a Medline research, to evaluate articles concerning ultrasound and locoregional anaesthesia published until April 2005. A total of 39 articles were reviewed. Technical procedures, the use of ultrasound guidance in epidural anesthesia, the application of this technique for peripheral nerve blocks, and its indications in pregnancy and in pediatric patients were considered. In these articles, all of the authors focused on the advantages of ultrasound guidance. With the help of this technique, correct catheter placement as close to the target as possible was obtained; the spread of local anesthetic administered around the nerve and its roots can be visualized, reducing the doses needed; in addition, it is possible to avoid the most common complications, such as intravascular injection, dura mater puncture, hematoma formation, and nerve injury. Ultrasound guidance is useful in facilitating peripheral and neuroaxial blocks and offers direct visualization of the target, adjacent structures, and local anesthetic spread. The advantages also include a decreased rate of complications and faster onset of blocks. Finally, ultrasound measurements can even result in suggestions to modify established block technique.