Neovascular glaucoma is a severe eye disorder classified as a secondary glaucoma and the most common of this type of disease. It is caused by a number of ocular and systemic conditions, which share the common element of retinal ischemia/hypoxia that initiates the subsequent release of angiogenesis factors. The most common causes of neovascular glaucoma are diabetic retinopathy and the occlusion of central retinal vein, of carotid artery, and of central retinal artery. More rarely, neovascular glaucoma can be secondary to eye tumors, traumas and uveitis. The present article reviews the stages of angiogenesis, forms of neovascularization and the clinical stages of the disease. Differential diagnosis is made and modern treatment of neovascular glaucoma is reviewed: treatment of iris neovascularisation, of extensive neovascular glaucoma and of end-stage neovascular glaucoma. Being a disease with poor prognosis, neovascular glaucoma should be well known not only by ophthalmologists but also by general practitioners, endocrinologists, neurologists, rheumatologist, and cardiologists. Only a timely diagnosis and adequate treatment can assure patients that they will preserve their vision and/or eye for a longer time.