Backround & aims: Intraocular pressure (IOP) rise is the most common complication of Nd YAG laser posterior capsulotomy. This study aimed to compare the effect of oral acetazolamide versus topical Co-biosopt in preventing IOP rise following Nd YAG laser posterior capsulotomy.Material and methods: The clinical trial was done on 200 patients who underwent laser Nd: YAG capsulotomy. First group received oral acetazolamide 250 mg q 6h and placebo drops q 8h and second group received Co-biosopt (timolol 0/5% and dorzolamide 2%) drops q 8h and oral placebo capsule q 6h. IOP was measured before and 24 hours after laser capsulotomy.Results: Comparing to hours before intervention, mean of IOP of right and left eyes 24 hours after capsulotomy was significantly decreased in both acetazolamide and Co-Biosopt groups (p=0.001).Conclusion: Considering oral acetazolamide little side effects and desirable IOP reduction of Co-Biosopt that has recently entered into Iran’s market with a domestic identical, this medication can be a relevant option for prevention of IOP rise after laser capsulotomy in patients with posterior capsular opacification.