Arthroscopically assisted anterior cruciate ligament(ACL) reconsturction provide a technique with less morbidity, less pin, less sacr, lower ris k of sepsis. The magnification offered by arthroscopic visualization also provide a clearer view, more precise location of anatomical landmarks, and the ability to place the graft in the exact anatomic sites. However, in order to accomplish all these goals, the surgeon must possess a high level of psychomotor skills, which take time and practice to develop. Wile this learning curve is being completed, there are occasion when complications will occur, and, realistically these may be difficult to avoid. The purpose of this study is to evaluate author's cases in which complication occurred during the endoscopic one-incision ACL reconstruction using the patellar tendon and to offer some tips on how to avoid them and how to salvage the situation if they do occur. We reviewed 22 complications (11 patients) out of 40 ACL reconstructions performed between May 1994 and December 1995. The complications were divergence(6), graft-tunnel mismatch(5), too anterior tibial tunnel(3), too anterior femoral tunnel(2), too posterior femoral tunnel(2), rotation of screw around the graft(2), guide pin breakage(1), bone plug retraction into the joint(1). It is suggested that arthroscopist should constantly try to avoid the intraoperative complications of arthroscopically assisted ACL reconstruction and follow the precautions and preventive measures recommended.