Dry eye has gained recognition as a public health problem given its high prevalence, morbidity and cost implications. Although dry eye is common and affects patients’ quality of life, only one medication, cyclosporine 0.05% emulsion, has been approved by the US FDA for its treatment. In this review, we summarize the basic science and clinical data regarding the use of cyclosporine in the treatment of dry eye. Randomized controlled trials showed that cyclosporine emulsion outperformed vehicles in the majority of trials, consistently decreasing corneal staining and increasing Schirmer scores. Symptom improvement was more variable, however, with ocular dryness shown to be the most consistently improved symptom over vehicle.