This randomized, investigator-masked, multicenter, parallel-design trial compared the IOP-lowering efficacy of bimatoprost 0.03% and travoprost 0.004% in African Americans with glaucoma or ocular hypertension. After a washout of all ocular hypotensive agents, patients were assigned to bimatoprost once daily (n=16) or travoprost once daily (n=15) for 3 months. Study visits were at baseline and at months 1, 2, and 3. Primary outcome measures were the percentage of patients who achieved selected target pressures and the mean reduction in IOP from baseline at month 3. Both drugs comparably lowered IOP, but bimatoprost was more likely than travoprost to allow achievement of every target pressure from 12 to 19 mm Hg at month 3. After 3 months, the mean IOP reduction from baseline was 8.4 mm Hg (34%) in the bimatoprost group and 7.9 mm Hg (30%) in the travoprost group. These results are being evaluated further in a larger clinical trial.