To determine the outcome of preoperative against-the rule (AR) astigmatism among 1,648 phacoemulsification and aspiration (PEA) procedures, we analyzed the postcataract time course of astigmatism over 6 months in 618 eyes divided into three groups. In preoperative AR astigmatism < 0.75 dptr (n=208) the astigmatism increase 1 week postoperatively was rapid. In preoperative AR astigmatism ≥1.5 dptr (n=185), no difference in the power of astigmatism was apparent between 1 and 3 months postoperatively. The third group (0.75 ≤ preoperative AR astigmatism < 1.5 dptr, n=143) showed intermediate characteristics. The eyes with preoperative low AR astigmatism showed exacerbation of astigmatism after the PEA procedure, whereas the degree of astigmatism, corneal curvatures and the rate of AR astigmatism became lower in the eyes with higher preoperative AR astigmatism.