Background <p>This study aimed to evaluate the histomorphological cellular and fibrotic responses in rat brain tissue following direct placement of platinum coils, simulating potential coil protrusion or extravasation scenarios encountered during endovascular treatment of ruptured intracranial aneurysms.</p> Methods <p>A burr hole was made in the biparietal bone region of 40 Winstar albino rats to pass through the dura and pia mater, and a platinum coil was placed in the interhemispheric area. The rats were sacrificed on days 3 and 10 to evaluate the changes in the acute and chronic periods, respectively. Subsequently, brain tissues were removed and histomorphological changes were examined.</p> Results <p>The lowest amount of reparative tissue in the treated area was formed in the coil + 3-day group, whereas the highest amount of reparative tissue was formed in the coil-free 10-day group. Further, the amount of reparative tissue in the coil-free 3-day group and the coil + 10-day group was high compared to the coil + 3-day group, whereas low compared to the coil-free 10-day group. These two groups (coil-free 3-day and coil + 10-day) were statistically similar to each other and different from the others.</p> Conclusıons <p>Platinum coil is expected to reduce the development of tissue reaction, which may be a disadvantage for the development of complete occlusion; however, it is important for reducing the possibility of thromboembolism and showing that the protruding coil has no irritating effect on brain tissue.</p>