OBJECTIVE To determine Schirmer wetting (tear flow) in patients before and after kidney transplantation where systemic cyclosporine was used as an immunosuppressive. METHODS Patients with end-stage renal disease who received living donor or cadaveric kidney transplants and simultaneous systemic cyclosporine were recruited. A 4-minute Schirmer test with topical anesthetic was performed in both eyes of each person before cyclosporine was initiated and three times after transplantation. The tear flow values from both eyes were averaged before analysis. RESULTS Tear flow increased significantly from precyclosporine levels of 19.4 +/- 1.5 mm/4 minutes (mean +/- standard error of the mean, n = 7; readings at 1 to 3 days before cyclosporine was begun) to 28.4 +/- 2.4 mm/4 minutes at 1 to 2 months after cyclosporine (P < 0.01), 26.4 +/- 2.0 mm/4 minutes at 3 to 5 months (P < 0.05), and 24.4 +/- 2.1 mm/4 minutes at 9 to 18 months (P < 0.05) after initiation of cyclosporine therapy. No relation existed between tear flow and systemic cyclosporine concentration. CONCLUSIONS Tear flow was significantly enhanced by systemic cyclosporine when given to renal allograft recipients as an immunosuppressive. The increased flow rate was sustained over the maximum follow-up of 18 months and indicates an unexpected, beneficial side effect of cyclosporine, even in the absence of a deficit in baseline tear production.