Abstract: A stabilizer is used to immobilize a portion of the heart or other organ to facilitate a surgical procedure such as anastomosis. The stabilizer comprises two, C-shaped, organ wall-contacting elements, hinged together so that they can form a continuous loop. The hinge allows the C-shaped elements to be separated so that, after surgery in which a tubular graft connected to the organ extends through the loop, the stabilizer can be released from the graft. The C-shaped elements are connected to a stem which consists of two lockably articulating parts, one of which is immediately connected to one of the C-shaped elements and aligned with the hinge axis. A spring-loaded sleeve, surrounding the last-mentioned part of the stem, has pins which engage recesses in the C-shaped parts to lock them in the closed condition, while allowing them to be opened quickly by manipulation of the sleeve. Removable, disposable pads form the organ wall-contacting surfaces.