The use of botulinum toxin is becoming increasingly popular, and application details are being examined in an effort to achieve more satisfactory results with fewer side effects. In the forehead area, the main considerations are the effacement of forehead wrinkles to a desirable extent and the prevention of complications such as ptosis of the eyebrow and upper eyelid. The frontalis muscle necessitates chemodenervation by botulinum toxin at multiple points for the desired effect. The dimensions of foreheads, and thus the frontalis muscle, differ from patient to patient. The effectiveness and side effects change according to whether the forehead is narrow or a wide. Therefore, no single application technique is best for all patients. For this study, the glabella-hairline distance was measured in 90 healthy adults. Patients with a vertical forehead length exceeding 70 mm were regarded as having a wide forehead, and the botulinum toxin was applied in three vertical lines in two split doses. On the other hand, individuals with a vertical forehead length of less than 60 mm were regarded as having a narrow forehead, and the toxin was applied in two split doses in three horizontal lines. The authors have found that in cases of wide or narrow foreheads, the effectiveness of the toxin increased, whereas the side effects such as brow asymmetry and ptosis were not encountered. Thus, they recommend the use of this technique for patients with wide or narrow foreheads.