Carbonic anhydrase inhibitors used in the treatment of glaucoma are rarely associated with blood dyscrasias. Several case reports of aplastic anemia with use of acetazolamide, and two cases with use of methazolamide, have appeared in the literature. This report documents two cases of aplastic anemia, at least one of which was almost certainly induced by the use of methazolamide, one case of agranulocytosis, and two cases of neutropenia related to the use of methazolamide. In each case several weeks to months elapsed between initiation of therapy and onset of reaction. This suggests that changes in patients' general medical condition should be continually monitored when using these drugs.