AbstractFifty‐six patients who underwent extracapsular cataract surgery were randomized in two groups with 28 patients in each group. Group 1 was treated with standard preoperative dilation regime and group 2 received in addition indomethacin 1% ophthalmic solution. Horizontal and vertical pupil diameter measurements were taken before capsulotomy, before exprimation of the lens nucleus and before lens implantation. The size of the pupil at the time of capsulotomy and at the time just before lens exprimation was greatest in the non‐indomethacin treated group, but at the time of lens implantation the pupil of the indomethacin treated group was greatest. It is concluded that even though indomethacin seems to be able to inhibit surgically induced miosis, probably through its inhibitory effect on prostaglandine synthesis, the effect is only marginal and from a clinical point of view it cannot be recommen