Topical corticosteroids are commonly used for decreasing inflammation after strabismus surgery. However the use of topical corticosteroids may be associated with several adverse effects. The aim of this study was to compare the relative effects of topical diclofenac with betamethasone in inflammation, wound healing and intraocular pressure following strabismus surgery. A single centre, single observer, prospective, randomized and single blind clinical trial of 43 patients undergoing strabismus surgery was carried out. Both postoperative treatments were instilled four times per day in the first week and two times per day in the second week postoperatively. Patient pain and discomfort, conjunctival chemosis, injection, conjunctival gap, and intraocular pressure were assessed at one day, one week, two weeks and four weeks after surgery. Since the first postoperative week the diclofenac group showed less discomfort and less conjunctival inflammation, edema, and conjunctival gap than the betamethasone group and these differences became statistically significant at the second week after surgery. There was not any significant difference between mean intraocular pressure of the diclofenac and the betamethasone group in any postoperative measurements. Diclofenac appears to be superior to corticosteroids in controlling the inflammatory responses and surgical wound healing after strabismus surgery. The maximal effect of diclofenac occurred at 2 weeks after surgery.