Although it is still unclear what the ideal angle of the tibial tunnel in the coronal plane should be when performing anterior cruciate ligament (ACL) reconstruction using the endoscopic single-incision technique, researchers have recently shown that erroneous placement of the tibial tunnel in the coronal plane can lead to graft laxity and loss of extension. We have developed a simple, reproducible technique to provide an acceptable angle of the tibial tunnel in the coronal plane when using the endoscopic single-incision ACL reconstruction technique by using bony landmarks. With the ACL guide parallel to the femur, the external portion of the tibial tunnel guide is rotated so that the guidewire starting point is made at the bisection of a line between the tibial tubercle and the posteromedial border of the tibia. We have confirmed this technique in cadaver studies with angles of the tibial tunnel less than 75 degrees in the coronal plane in all cases. In addition, we have used this technique with good clinical results in over 100 ACL reconstructions.