In order to determine normal outflow facility and aqueous humor production values in Lewis rats, we established methods of measuring aqueous humor dynamics in this animal.Outflow facility was determined using anterior chamber infusion with constant pressure. Aqueous humor production was determined by a technique of dilution with FITC-albumin.The mean outflow facility was 0.044 +/- 0.01 microliter/min/mmHg. Rats weighing less than 300 g had lower values than did rats weighing more than 300 g (0.034 +/- 0.006 microliter/min/mmHg vs 0.050 +/- 0.015 microliter/min/mmHg, P = 0.009). The mean aqueous humor production was 0.350 +/- 0.110 microliter/min. The turnover rate of aqueous humor production per minute was 2.23%.Anterior chamber infusion with constant pressure and the FITC-albumin method allow measurement of the outflow facility and aqueous humor production in Lewis rats. These methods may be useful in assessing aqueous humor dynamics when rats are used as a glaucoma model.