Malignant glaucoma is a rare but a serious glaucoma responsible for the loss of one or both the eyes. Malignant glaucoma occurs immediately after glaucoma surgery especially in primary angle-closure glaucoma (PACG) with flat anterior chamber, also can occur after cataract or any intraocular surgery or any anterior segment laser surgery, or even rarely in nonoperated eyes. Also it can occur either in phakic, aphakic or pseudophakic. Clinical importance, onset, other clinical forms, and pathophysiology are explained. Clinical signs and symptoms include predisposition. Differential diagnosis presents choroidal separation, papillary block, iridovitreal block, and suprachoroidal hemorrhage. Investigations carried out are direct ophthalmoscopy, tonometry, gonioscopy, and perimetry. Chandler’s three-step surgical confirmation procedure is described.