Mallet finger lesions are common. The diagnosis of mallet finger is essentially clinical, the patient's recent history includes the mechanism of injury. A radiographic lateral and anteroposterior views of the DIPJ usually see bony avulsion of distal phalanx or it may be a ligamentous injury with normal bony anatomy, Wehbe and Schneider described a method to measure the size and displacement of the bony fragment. The aim of this study is to compare the results between of conservative and K-wire pinning management of acute mallet finger Doyle type I in adult patients. Patients were divided into two groups. Group (A) were treated with aluminum orthosis that immobilized the DIPJ in full extension for six weeks. And Group (B) were treated with percutaneous fixation of the distal interphalangeal joint using a smooth Kirschner wire. No external splint age was used and the wire was removed after six weeks. A total of 40 patients suffering from acute mallet finger type I Doyle's classification admitted in orthopedics and traumatology department of Sohag university hospital from February 2019 to November 2019. All patients had Follow up radiographs taken of the affected finger at one week, four weeks, and eight weeks. Functional outcomes were determined using Crawford's evaluation criteria. The final extensor lag was significantly better in the pin group (12.3 vs 6.6°). The amount of improvement between the groups was statistically significant and in favor of percutaneous pinning (16.15 vs 20.55°), also the flexion loss was lesser in pin group (5.4 vs 4.1°). The optimal treatment for mallet finger injuries remains controversial in the literature. Many orthotic devices for conservative management and surgical techniques have been described in the past. This study shows that closed reduction by use of K-wires provide functionally better result in acute mallet finger cases. Surgical treatment by a single k-wire is better than conservative treatment as regard clinical and radiological results. Conservative technique may have less complications, but the difference in final clinical results is in favor of surgical treatment