Over the past decade, there has been a resurgence of interest in techniques of rehabilitation of the injured knee. Technologic advances have provided instruments that yield objective measurements so that appropriate staging can be done as part of the rehabilitation plan. Research in multidisciplinary fields has provided data that currently allow a rational physiologic approach to progressive care of the injured lower extremity. No longer is the adage "work it out and let's see how it goes" appropriate care for the injured knee. Starting with the proper diagnosis, rehabilitation begins at the time of injury and is specific for both the patient and the injury. A time frame is established for the rehabilitation, with progressive monitoring to allow gradual return to activity and the goals of both the patient and the surgeon taken into consideration. The management of knee injuries, whether from an overuse stress syndrome or following severe trauma with major ligament disruption, deal with the management of the inflammatory response. Since we do not know the exact time period for full mechanical competence following ligament healing, gradual assessment of objective data is necessary before return to full vigorous activity. Improved methods of rehabilitation allow patients to feel a sense of an active, dynamic process during which they are made to realize that much of their total improvement is up to them, under the guidance of the physician and therapist. The maintenance of function and fitness in uninjured extremities also allows for a feeling of well-being. Techniques now available make this often-forgotten phase of treatment a more pleasurable one and one that must be considered as much a part of knee injury management as is the knee immobilizer or the surgeon's scalpel.