STUDY DESIGN: A systematic review of randomized controlled trials. OBJECTIVE: To determine the efficacy and adverse effects of conservative treatments for people who have lumbar disc herniation with associated radiculopathy (LDHR). SUMMARY OF BACKGROUND DATA: Although conservative management is commonly used for people who have LDHR, the efficacy and adverse effects of conservative treatments for this condition are unclear. METHODS: We searched 10 computer databases for trials published in English between 1971 and 2008. Trials focusing on people with referred leg symptoms and radiologic confirmation of a lumbar disc herniation were included if at least 1 group received a conservative and noninjection treatment. RESULTS: Eighteen trials involving 1671 participants were included. Seven (39%) trials were considered of high quality. Meta-analysis on 2 high-quality trials revealed that advice is less effective than microdiscectomy surgery at short-term follow-up, but equally effective at long-term follow-up. Individual high-quality trials provided moderate evidence that stabilization exercises are more effective than no treatment, that manipulation is more effective than sham manipulation for people with acute symptoms and an intact anulus, and that no difference exists among traction, laser, and ultrasound. One trial showed some additional benefit from adding mechanical traction to medication and electrotherapy methods. Adverse events were associated with traction (pain, anxiety, lower limb weakness, and fainting) and ibuprofen (gastrointestinal events). CONCLUSION: Advice is less effective than microdiscectomy in the short term but equally effective in the long term for people who have LDHR. Moderate evidence favors stabilization exercises over no treatment, manipulation over sham manipulation, and the addition of mechanical traction to medication and electrotherapy. There was no difference among traction, laser, and ultrasound. Adverse events were associated with traction and ibuprofen. Additional high-quality trials would allow firmer conclusions regarding adverse effects and efficacy.