The utilization of endoscope-assisted surgery is becoming a more common modality for the surgical treatment of subdural collections. Considering the inflexible construction of the rigid endoscope, it's not clear where to perform the optimal craniotomy. Twenty four craniotomies (3 cm diameter) were performed in 8 hemicrania. The craniotomies were placed 1 cm front and behind the coronal suture and to the point where the parietal bone was the most convex. The craniotomies in the anterior (C1) and posterior (C2) of the coronal suture were in the mid pupillary line, while the posterior craniotomy (C3) was just lateral to the midpupillary line. At first, subdural distances measured, and then the distances from the craniotomy to the anterior, posterior, medial, and lateral directions in which endoscope could reach the farthest without the damage to the parenchyma were measured. The subdural distance was significantly deeper in C3 than C1 (P = 0.001); however, there was no difference between C3 and C2 (P = 0.312). The distance that could be reached with C3 was higher than C1 in anterior, posterior, lateral, and medial directions (P ≤0.001, 0.037, <0.001, and <0.001, respectively). The distance that could be reached with C3 was higher than C2 in anterior, posterior, lateral, and medial directions (P < 0.001, 0.02, 0.01 and <0.001, respectively). In subdural hematomas, especially that covers all surface of the hemisphere, the most suitable craniotomy is the posteriorly placed craniotomy to reach the most extended projection in anteroposterior line of the hematoma.