Topical cyclosporin 2% in olive oil was investigated for its possible immunoregulatory role on the dry eye state in patients with secondary Sjögren's syndrome. The study was a randomized, double-masked, placebo-controlled trial. Thirty eyes of 15 patients were randomized to undergo treatment with topical cyclosporin in olive oil and 30 eyes of the other 15 patients received a placebo, which was the sterile olive oil used as a vehicle for the cyclosporin. The effect of the 2-month long treatment with either medication on the status of the dry eye state was measured by Schirmer-I test, tear film break-up time and rose bengal staining. There was a significant increase in the break-up time and a significant decrease in rose bengal staining score between the cyclosporin and control groups at the end of the 2-month study period (p < 0.01). Schirmer-I test remained unaffected (p > 0.05). These results probably indicate that topical cyclosporin modulates the goblet cell function in secondary Sjögren's associated keratoconjunctivitis sicca and through this mucus enhancing action or some other mechanism not yet known, helps to maintain the structural integrity of the epithelium.