Thirty-two different cannabinoids were tested for their ability to reduce intraocular pressure (IOP) in the rabbit. These included many of Δ9-and Δ8 -THC derivatives and metabolites along with other natural and synthetic cannabinoids. In addition, some non-cannabinoid constituents of Can-nabis were screened using the same model. All compounds were administered intravenously, while only a few were tested topically in mineral oil. Water soluble derivatives of Δ9– and Δ8-THC were prepared and tested topically in aqueous solution. The data revealed that certain derivatives of Δ9– and Δ8-THC were more active in lowering IOP than the parent cannabinoids. In addition, compounds other than Δ9– and Δ8-THC and their derivatives were shown to have activity.