AIM: To evalaute the effect of fixed-combination latanoprost 0.005%/timolol maleate 0.5% and dorzolamide hydrochloride 2%/timolol maleate 0.5% on postoperative intraocular pressure after phacoemulsification cataract surgery. METHODS: This study is a prospective, randomized, double-masked and placebo-controlled. The study included 90 eyes of 90 patients which were scheduled to have phacoemulsification surgery. Patients were randomly assigned preoperatively to 1 of 3 groups (30 eyes of 30 patients). Two hour before surgery, the patients received one drop latanoprost/timolol (group 1), dorzolamide/timolol (group 2) and placebo (group 3, control group). The IOPs were measured at preoperative and postoperative 4, 8, and 24 hours. RESULTS: The preoperative mean intraocular pressure was not statistically significant between both drug groups and control group. In group 1 and 2, the postoperative mean IOP [group1: (14.03±3.15)mmHg and group 2: (14.16±4.43)mmHg] at 24 hours were significantly lower than the control group [(16.93±3.70)mmHg, (P<0.05)]. In addition, the postoperative mean IOP of group 1 [(14.90±3.69)mmHg] at 8 hours was significantly lower than the control group [(17.70±3.89)mmHg, (P<0.05)], but there was no significant difference between group 2 [(16.16±5.23)mmHg] and control group at 8 hours (P>0.05). CONCLUSION: When compared with placebo, the use of preoperative fixed combination of latanoprost/ timolol and dorzolamide/timolol is an effective method for preventing intraocular pressure elevation in 24 hours after phacoemulsification surgery, but did not completely prevent IOP spikes.