The tear film break-up time is usually measured with the lacrimal fluid stained with fluorescein. With the staining methods currently recommended the break-up time is difficult to reproduce. In the study described here, the break-up times with different staining methods were compared. The reproducibility of the break-up time was measured shortly after staining and one minute thereafter. The best reproducibility achieved in this study was when the tear fluid was stained with 1 microliter of 5% Na-fluorescein solution.