Ciliary block (malignant) glaucoma is a rare complication of cataract surgery. In eyes with narrow angles and acute glaucoma, ciliary block must be differentiated from pupillary block to provide appropriate therapy. We review two cases of ciliary block glaucoma following uncomplicated extracapsular cataract extraction with posterior chamber lens implantation. Previous filtering procedures in these cases resulted in protracted shallowing of the anterior chamber, possibly contributing to the pathogenesis of ciliary block. In addition, the operative trauma of cataract surgery may have resulted in the separation of the vitreous base from the pars plana. Misdirected aqueous humor then could have entered the vitreous body, displacing the iris-pseudophakos diaphragm forward, and resulting in the acute glaucoma. Vitrectomy, which resolved the acute glaucoma, is valuable in treating ciliary block glaucoma.