Objective To study the effect of platelet-rich plasma (PRP) on repairing chronic wounds of lower l imbs. Methods From May 2007 to November 2007, 47 patients suffering from chronic wounds of lower l imbs were treated. There were 41 males and 6 females, aged from 15 to 68 years (43.2 years on average). The disease was caused by tibiofibulafracture in 20 cases, calcaneus fracture in 4 cases, metatarsal fracture in 1 case, multiple open fracture of lower l imbs in 3 cases, tibia osteomyel itis in 10 cases, femur osteomyel itis in 1 case, soft tissue injury of ankle in 4 cases, infection after amputation in 2 cases, infection after foot orthomorphia in 1 case, and infection after calcaneus tendon neoplasty in 1 case. Their chronic wounds did not healed after 2 to 4 months of therapy. Among them, chronic wounds compl icated with fracture nonunion in 23 cases and positive bacterial culture result in 38 cases. Debridement and autogenous PRP gel injection were appl ied every 2 months and for twice. Results The patients were followed up for 4 months after the first PRP injection. Two months after the first PRP injection, chronic wounds contracted significantly in 34 patients with purulence and necrosis tissue cleaned up, circulation of soft tissue improved and exposed bone or muscle tissue covered by neogenetic granulation. No patient was completely cured. Two months after the second PRP injection, the average coverage rate was 79.3% ± 18.0%, the total cure rate was 29.8%. The volume of the chronic wounds decreased by (9.3 ± 4.9) mL after PRP therapy (2.5 ± 2.7) mL when compared with (11.8 ± 5.6) mL of before therapy, showing significant difference (P lt; 0.05). X-ray photograph showed that among the 23 cases of fracture nonunion, fracture healed completely in 9 cases; bony callus formation increased obviously in 12 cases; no significant change was observed in 2 cases. No aggravated sign of osteomyel itis was notified. Positive results of bacterial culture reduced to 15 cases. Conclusion PRP efficiently enhances the recovery of soft tissue defect and speeds up the chronic wounds heal ing oflower l imbs.