The postthrombotic syndrome (PTS) is a frequent complication of deep venous thrombosis (DVT). Clinically, PTS is characterized by chronic, persistent pain, swelling, and other signs in the affected limb. Rarely, ulcers may develop. Because of its prevalence, severity, and chronicity, PTS is burdensome and costly. Preventing DVT with the use of effective thromboprophylaxis in high-risk patients and settings and minimizing the risk of ipsilateral DVT recurrence are likely to reduce the risk of development of PTS. Daily use of compression stockings after DVT might reduce the incidence and severity of PTS, but consistent and convincing data about their effectiveness are not available. Future research should focus on standardizing diagnostic criteria for PTS, identifying patients at high risk for PTS, and rigorously evaluating the role of thrombolysis in preventing PTS and of compression stockings in preventing and treating PTS. In addition, novel therapies should be sought and evaluated.