Intraocular melanomas are not common entities but often lead to secondary glaucoma. Intraocular melanomas should be considered in the differential diagnosis of patients with unilateral glaucoma. Occasionally, the workup of unilateral glaucoma leads to a diagnosis of an intraocular melanoma. Intraocular melanomas represent the majority of intraocular tumors. The prevalence of intraocular melanomas as well as associated secondary glaucomas will be reviewed. The workup needed for unilateral glaucoma will be covered in detail. Treatment options for secondary glaucomas include topical and oral medications as well as argon laser trabeculoplasty and transscleral cyclophotocoagulation.