Disclosed herein is method of treating glaucoma or ocular hypertension comprising administering a prostaglandin agonist and a second therapeutically active agent to a mammal in need thereof, wherein said second therapeutically active agent is selected from: β-Blockers, Adrenergic Agonists, non-selective adrenergic agonists, α2-selective adrenergic agonists, Carbonic Anhydrase Inhibitors, Cholinergic Agonists, direct acting cholinergic agonists, chlolinesterase inhibitors, Glutamate Antagonists, Ca2+ channel blockers, Prostamides, Prostaglandins, Cannabinoids, and combinations thereof. Compositions and medicaments containing a combination of these two active agents are also disclosed.