Reflex sympathetic dystrophy (RSD) of the knee frequently does not present with the classic combination of signs and symptoms seen in the upper extremity. Pain out of proportion to the initial injury is the hallmark symptom. Symptom relief by sympathetic block is the current standard for confirmation of the diagnosis. Because invasive diagnostic procedures, such as arthroscopy, are likely to increase symptoms, evaluation with a noninvasive diagnostic modality, such as magnetic resonance imaging, is preferred. Generally, RSD should be treated before surgical intervention to correct any underlying intra-articular pathologic condition. However, surgery may sometimes be necessary before RSD symptoms resolve; in these cases, use of intra- and postoperative continuous epidural block can be successful. The initial treatment of RSD of short duration should be conservative; physical therapy modalities, including exercise and contrast baths, and non-steroidal anti-inflammatory drugs are indicated. In the authors' experience, an indwelling epidural block using bupivacaine for several days followed by use of a narcotic agent, combined with functional rehabilitation, is the most effective management when noninvasive treatment has failed. Surgical sympathectomy can be successful, but should be reserved until repeated lumbar sympathetic block or more than one trial of inpatient epidural block has failed. Early diagnosis and early institution of treatment (prior to 6 months) are the most favorable prognostic indicators in the management of RSD.