A consecutive series of 248 eyes undergoing extracapsular cataract surgery and posterior chamber lens implantation were evaluated. One hundred eight eyes had the implant placed with the convex side posterior and 140 with the convex side anterior. The incidence of capsulotomy required in the convex posterior group was significantly less than in the convex anterior group, 17.6% versus 29.3% (P value less than 0.05). The type of posterior capsule opacification in the two groups was also different. In the convex posterior group, a smooth fibrous type of capsular opacification predominated; in the convex anterior group, epithelial proliferation and pearl formation as well as wrinkling of the capsule frequently occurred. The difference in opacification was reflected in the preoperative visual acuity: convex posterior 20/80, convex anterior less than 20/200 (P less than 0.05).