Rupture of extensor pollicis longus can result from complication of distal radius fracture(including Colles' fracture) and rheumatoid arthritis, and stab injury on the radial side of the wrist, but in delayed cases, it is difficult to reconstruct its perfect function with direct end-to-end repair. Many authors tried to reconstruct E.P.L. with several methods such as tendon transfer with E.I.P. or E.C.R.L., and free tendon graft. The authors treated eighteen patients of ruptured E.P.L. with E.I.P. tendon transfer at Kyungpook National University Hospital from February 1983 to June 1990, and analyzed them clinically. The results obtained were as follews;l. Among 18 cases, 8 cases were due to distal radius fracture, 5 were stab injury, 3 were direct contusion and 2 were rheumatoid arthritis. 2. Period from rupture to operation was 6 years in the longest and 20 days in the shortest. 3. On the operative field, the ruptured portion of E.P.L. was at the level of radial Lister's tubercle in 16 cases. 4. Pulvertaft technique was used in all cases, except one(end-to-end anastomosis). 5. In postoperative care, the short arm thumb spica cast was kept for 4 weeks and active exercise for 3 weeks, and at postoperative 3 months, the patients had satisfactory extension of thumb without disturbance of extension of index finger. 6. According to the functional results of Riddel, 11 cases were excellent, 4 cases were good, 1 case was fair and 1 case was poor. But, the one case of end-to-end anastomosis was ruptured at 5 weeks after operation.