· Background: Our objective was to estimate the agreement between two different ultrasound biomicroscopes (UBMs) and to evaluate the clinical implications of the measurements obtained. · Methods: We measured the anterior chamber depth, trabecular-iris angle, angle opening distance at 250 and 500 µm from the scleral spur, iris thickness and scleral-iris angle using the Humphrey UBM model 840 and Rion UBM UX-02 in 25 eyes of 25 normal volunteers. · Results: No significant difference was found in the mean values of any parameters measured by the Humphrey and Rion systems. Correlation coefficients of greater than 90% were observed for the parameters studied. Each system showed high reproducibility for all measured parameters. There were significant differences between the two systems in coefficients of variation for all parameters measured except the anterior chamber depth. · Conclusions: The parameters measured with the Humphrey and Rion systems showed correlation coefficients of greater than 90%. The Humphrey system showed better reproducibility than the Rion system.