Tear volume and turnover rate were measured in 31 normal eyes using a newly designed objective fluorophotometer. After instillation of 1 microliter of 50,000 ng/ml fluorescein solution, its concentration in the lower marginal strip was measured every minute for 10 minutes after instillation. The tear volume and the tear turnover rate were determined using the method of Mishima et al. (Invest. Ophthalmol. Vis. Sci., 1966). The tear volume in this study was 12.4 +/- 6.2 microliters, initial turnover rate was 31.5 +/- 14.4%/min., and basal turnover rate was 24.0 +/- 14.2%/min. (Mean +/- SD). There were no significant differences in sex, age or use of contact lens. We also measured the tear volume and turnover rate using 5 microliters of 10,000 ng/ml fluorescein solution in the same way. The result turned out to be significantly higher, suggesting that minimal irritation is required for evaluating the tear flow.