Septic tenosynovitis continues to be a serious condition of the hand. Complications, sometimes necessitating amputation, are not uncommon. We studied the anatomic arrangements of the flexor tendon sheaths and were able to demonstrate different synovial compartments within the one osteofibrous tendon sheath. This has important consequences for surgical therapy. 48 Patients are reported operated on for tendon sheath infection over a 10-year period. All data influencing the end-result are analysed, with particular attention to delay in operative treatment, the results of bacterial cultures, the use of antibiotics and the surgical technic itself. When tenosynovitis is suspected, immediate drainage of all the different compartments of the tendon sheath is required.