In this review of recent articles on ocular toxicology, the author concentrates on undesirable effects on the eye induced by systemically used xenobiotics. These effects include increased tear flow elicited by systemic cyclosporine; uveitis associated with inactivated influenza vaccine, intravenous immunoglobulins, or skin tattoos; iritis associated with intravenous streptokinase; corneal epithelial erosion associated with the use of an alcohol-based antimisting spray; decreased color vision associated with workplace exposure to perchloroethylene, or to digoxin; myocardial ischemia induced by topical atropine; and systemic exposure to cyclopentolate after topical instillation. Ocular irritation associated with systemic use of 5-fluorouracil may be attenuated with prophylactic ice packs. At doses evaluated for treatment of choroidal neovascularization, systemic alpha interferon leads to toxicity in multiple organ systems. Promethazine precipitates when injected into intravenous lines with fluorescein. No drug achieves ultimate efficacy or ultimate safety. Thus, the decision to employ a given therapy involves a physician's evaluation of its therapeutic index-the ratio between efficacy and toxicity.