Anal endosonography (US) is a valuable tool to represent the normal anatomy of the anal canal and also to reliably examine patients with anal conditions. Our series consisted of 40 patients with suspected inflammatory and traumatic conditions of the anal canal submitted to anal US, which showed the presence of abscesses in 18 patients with suspected anal canal inflammation. A fistula was associated in 14 of the 18 patients and US after air injection easily showed a cutaneous orificium in 6 of the 14 patients. Anal US showed the presence and site of all abscessual foci and fistulae, also identifying the inner orificium and the involvement of muscular sphincteral structures, which is useful information to plan the most appropriate medical or surgical treatment. As for traumas, anal US is also a useful tool for identifying sphincteral injuries secondary to blunt trauma and for following-up sphincteral reconstruction with graciloplasty. Twenty-two patients with suspected sphincteric trauma were examined and anal US showed a sphincteral injury in 7 of 13 patients with acute postpartum-related symptoms; the clinical picture was ascribed to postpartum stretching of the pudendal nerve in 6 other patients. Finally, this method can be very useful in the follow-up of anal diseases, both to study surgical drainages and in the postoperative study of anal fistulae.