We compared the changes in corneal astigmatism after phacoemulsification and intraocular lens implantation in 93 consecutive eyes with unsutured 4-mm superior scleral tunnel incisions to those through 105 consecutive eyes with unsutured 3.2- to 3.5-mm temporal corneal tunnel incisions. Keratometry measurements were obtained preoperatively and at postoperative day 1, week 1, and week 6. Group differences in scalar and vector astigmatism were compared by using analysis of variance methods. Mean scalar astigmatism in the scleral incision group changed from preoperative astigmatism by 0.65 diopter at postoperative day 1, 0.37 diopter at postoperative week 1, and 0.13 diopter at postoperative week 6. Mean scalar astigmatism in the corneal incision group changed from preoperative astigmatism by 0.39 diopter at postoperative astigmatism by 0.39 diopter at postoperative day 1, 0.21 diopter at postoperative week 1, and 0.13 diopter at postoperative week 6. Mean vector astigmatism in the scleral incision group changed 1.26 diopters at 80 degrees at postoperative day 1, 1.05 diopters at 83 degrees at postoperative week 1, and 0.42 diopter at 103 degrees at postoperative week 6. Mean vector astigmatism in the corneal incision group changed 0.77 diopter at 90 degrees at postoperative week 1, and 0.61 diopter at 89 degrees at postoperative week 6. The differences were statistically significant (P = .003) only by vector analysis at the postoperative day 1 examination. We found significantly greater with-the-rule change in astigmatism in the scleral incision group than in the corneal incision group on the first postoperative day. The effect disappeared by the sixth postoperative week.