Only in the last lew years (the investigation of the subtalar joint by artrography gained its own place in the diagnosis of tarsal diseases. This kind of roentgengraphic technique has been applied in the clinical routine by Meyer and Garcia in 1981. In this paper the Authors, after reviewing briefly the anatomy of the subtalar joint, together with the peri-articular and ligamentous structures, discuss the arthrographic technique in detail. This technique is mainly addressed to investigate the subtalar joint and, indirectly, the content of sinus tarsi; the arthrography is simple but it does require some experience. The patient lies on the opposite side requested lor the examination. First of all a local anaesthetic is given; then a sterile area is limited; alter that water soluble contrast medium is injected by means of a syringe pointed at 1.5 cm proximally to the fibular malleolus tip and 1.5 cm behind the posterior ridge of the fistula. The direction of the needle is 45° oriented on all plains. The needle is introduced in the posterior side of the subtalar joint, in the posterior pouch, and the contrast medium is injected after checking the correct position of the needle by an image intensifier. Two or three ml of contrast medium are generally requested as far as one perceive resistance to injection. Radiographs are taken in the following views: 1) a lateral view of the foot; 2) an oblique view with the leg in 15° internal rotation; 3) an oblique view with (the leg in 45° internal rotation; 4) an oblique view with the leg in 45° external rotation; 5) a lateral view with the foot in forced dorsal flexion; 6) a lateral view with the foot in forced plantar flexion; 7) further views possibly needed. The ordinary arthrography shows the following features: 1) omogeneous filling of the articular space; 2) free and clearly outlined spaces all around the joint; anteriorly one may generally observe several micro cul-de-sac projecting towards sinus tarsi due to the presence of fat tissue and synovial recesses; 3) wide mobility of the recesses in stress-radiograms; 4) possible anatomical connections among subtalar joint and tibio-talar joint, mid-tarsal joints or with the tendon sheahts of the peronei or flexor hallucis longus; 5) articular cartilage looking like negative images, smooth and with an average 1-2 mm thickness. The sinus tarsi syndrome, particularly the post-traumatic one, constitutes the primary indication lor the arthrography. The features that we can observe in this case are the following: the fihrosis of the sinus tarsi fat tissue and enlargement of the synovial micro cul-de-sac. The arthrographic technique, besides its clinical application, resulted to be of great importance in forensic medicine for the assessment of the object ive data of a svndrome characteri/ed mainly by subjective symptoms. In the case of an acute traumatic disease the arthrographic technique can assess interosseous ligament lesions, revealed by an escape of the contrast medium in the sinus tarsi. This technique is resolutive in the case of retractile capsulosis since it gives the typical picture of obliteration of all recesses. The examination of the articular surfaces is not so easy because of the superposition of the injected recesses. Summing up the Authors consider the arthrographic technique as a quite useful investigation tool for all the not vet deeply studied tarsal diseases.