Abstract: Significant success in alleviating the symptoms of glaucoma is achieved by orally administering to a glaucoma sufferer a therapeutically effective, but sub-psychotropic dose of tetrahydrocannabinol (THC), which is the most active ingredient in marijuana. The most significant results are achieved when this form of treatment is combined with conventional types of anti-glaucoma treatment, although in a limited number of cases, THC therapy alone proved successful. Also disclosed is a dosage unit form for THC comprising a suitable dose of THC in combination with an innocuous diluent such as fructose.