We present 32 cases of dysfunction of the Björk-Shiley valvular prosthesis, representing 3.01% of the 1,063 BS prostheses implanted at this clinic. The complications observed were thrombosis of the prosthesis, suture dehiscence with or without endocarditis and disc-suture interference. In selected, favourable cases, we prefer thrombectomy with generous washing of the prosthesis and rotation of the disc, without removal of the disc from the prosthesis. Furthermore, when the dehiscence does not exceed 1/3 of the circumference of the ring, we have achieved very good results with single sutures supported on Teflon patches. Subsequent failures of this procedure were not of a technique nature, but rather due to the poor condition of the patients. In situations of clinical emergency, the diagnosis of valvular dysfunction may suffice as indication of surgery, further diagnostic measures being postponed in view of the data of the physical exploration.