Background: The dynamic hip screw (DHS) is widely used in treating the intertrochanteric fractures of the femur in old patients. The positions of the lag screw in the femoral neck and the distance between the tip of the lag screw and the apex of the femoral head are very important for the procedure success. Objective: To assess lag-screw positions rule on failure of fixation intertrochanteric femur fractures. Patients and Methods: This was a case presentation study contained twenty patients aged ≥50 with unstable types of intertrochanteric fractures, and had been subjected to dynamic hip screws. Results: This study included (13) females and (7) males whose ages ranged between (58) to (86) years, Failure of fixation seen in 15 cases (75%) of all cases and union seen only in 5 cases (25%). The mean tip apex distance (TAD) was significantly longer when with fixation failure (p= 0.002). Relation of Location of Lag Screw to fixation failure had no statistically significant difference. Tip apex distance(TAD)was significantly longer among the studied cases with inferior-centeral (I-C) location of lag screw as compared with centeral-centeral (C-C) location of lag screw (p= 0.006). Conclusion: The Tip apex distance (TAD) wasan easy effective way which was very important to determine the location of the screw. Regardless place of the guide-pin was placed as long as the aimed position results in a tip-apex distance of greater than twenty-five millimeters. So, it was recommended to reconsider the guide pin reduction and redirection.