To evaluate the effect of 5-fluorouracil (5-FU) appl ied topically on preventing adhesion andpromoting functional recovery after tendon repair. Methods From August 2003 to June 2007, 48 patients with flexor tendonrupture of the fingers by sharp instrument were treated and randomly divided into two groups. In 5-FU group, 39 fingers of 26 patients included 17 males and 9 females, aged (29.3 ± 9.8) years; the locations were zone I in 19 fingers and zone II in 20 fingers; single finger was involved in 12 cases and more than 2 fingers were involved in 14 cases; and the time from injury to operation was (2.4 ± 1.6) hours. In control group, 36 fingers of 22 patients included 14 males and 8 females; aged (26.1 ± 8.7) years; the locations were zone I in 16 fingers and zone II in 20 fingers; single finger was involved in 10 cases and more than 2 fingers were involved in 12 cases; and the time from injury to operation was (2.1 ± 1.8) hours. No statistically significant difference was found in constituent ratio of age, gender, injured fingers and their zones, between two groups (P gt; 0.05). The repair site in 5-FU group was given 5-FU at a concentration of 25 mg/mL with a soaked sponge, and the synovial sheath of the repaired site was wrapped with the 5-FU-soaked sponge for 1 minute for 4 times after the tendons were repaired; normal sal ine was used in the control group. Results Wound healed by first intention and no infection and tendon rupture occurred in two groups. The patients were followed up for 3-8 months (mean 4.1 months) and 3-8 months (mean 3.9 months) in 5-FU group and in control group respectively. The functional recovery degrees of the fingers were evaluated with total active movement (TAM) evaluation system. In 5-FU group, the results were excellent in 22 fingers, good in 13 fingers, fair in 3 fingers and poor in 1 finger; the excellentand good rate was 89.7%. In control group, the results were excellent in 11 fingers, good in 15 fingers, fair in 9 fingers andpoor in 1 finger; the excellent and good rate was 72.2%. There was statistically significant difference in the functional recovery degrees of fingers between two groups (P lt; 0.05). The 2 fingers which had a poor result in 5-FU group and control group were served with tenolysis was performed in 2 cases having poor results after 6 months of operation and had an excellent result at last. Conclusion 5-FU appl ied topically can reduce tendon adhesions after the ruptured tendon repair.