Displacement of the mandible 2-2 1/2 years after oblique sliding osteotomy of the mandibular rami is reported. Stability of the osteotomy site has been assumed to be complete much earlier, however. In the present stereo radiographic study mobility at the osteotomy site was recorded as late as 2 years after surgery. No sign of delayed healing was recorded in the plain radiographic examination. It seems possible that relapse after oblique sliding osteotomy continues as long as the functional matrix can influence an unstable osteotomy site. As plain radiography does not give full information on the quality of bone, the stability of the osteotomy site can not be assessed by this method.