OBJECTIVE To compare intraocular pressure (IOP) lowering efficacy of bimatoprost 0.03% / timolol 0.5% fixed combination (BTFC) and other combinations of glaucoma drugs (bimatoprost, latanoprost 0.005% / timolol 0.5% fixed combination, separate use of travoprost 0.004 % and timolol 0.5 %) in patients with glaucoma. METHODS Fifty-three patients with glaucoma were divided into 3 groups according to their original glaucoma therapy. BTFC was used by the patients for a period of 3 months. After 1 week, 1, 2 and 3 months, the diurnal IOP curves were performed. Side effects of the new treatment were recorded and compared to the original therapy. RESULTS The mean diurnal IOP reduction in the group of patients switching from bimatoprost to BTFK reached 4.4 +/- 2.28 mm Hg (p < 0.01). In the group of patients initially on latanoprost / timolol fixed combination, the IOP decreased with BTFK by 2.3 +/- 1.5 mm Hg (p < 0.01). Changing therapy from travoprost / timolol seperate combination to BTFK caused an IOP decrease by 2.3 +/- 1.5 mm Hg on average (p < 0.01). Conjunctival hyperemia with initial therapy was experienced in 33% of patients in our study group. With BTFK application, the hyperemia improved in 69% of these patients, got worse in 12.5% and remained unchanged in 19% of the patients. Patients found the BTFK better than the original medication in 37.5% of cases, the same in 52% and worse in 10.5%. Five patients terminated the study earlier due to poor IOP compensation or marked side effects of BTFK. CONCLUSIONS In all three groups of glaucoma patients there was a significant and prolonged decrease in IOP after treatment with BTFK. The use of BTFK was accompanied by smaller incidence of conjunctival hyperemia compared to isolated bimatoprost or travoprost / timolol combination.