To evaluate the effectiveness of postoperative adjustment of a continuous suture in reducing postoperative astigmatism in patients who have undergone penetrating keratoplasty. We prospectively analyzed refraction, keratometric and topographic findings, and complications before and after adjustment of a continuous suture in 14 eyes of 14 patients who had undergone penetrating keratoplasty. The mean age was 36.0+/-15.4 years and the mean follow-up duration was 15.2+/-6.1 weeks after suture adjustment. The astigmatism significantly changed after suture adjustment from 6.20+/-2.47D to 3.80+/-2.57D in refractometer, from 5.75+/-2.45D to 2.95+/-2.42D in keratometer, and from 6.49+/-2.34D to 3.80+/-2.61D in topography. Similar results were made in 6 eyes who had undergone secondary suture adjustment for the remnant astigmatism. In comparison of astigmatic changes according to the interval from penetrating keratoplasty to suture adjustment, no significant difference was found between the two groups (less than 4 weeks vs more than 4 weeks). The reduced astigmatism after suture adjustment maintained stably until the final follow-up. The adjustment of a continuous suture after penetrating keratoplasty is effective in reducing the postoperative astigmatism while maintaining the corneal integrity.