To compare biometry measurements and intraocular lens (IOL) power calculations obtained by a new optical A-scan interferometer biometer (Galilei G6) (new biometer) and a partial coherence interferometer biometer (IOLMaster 500) (reference biometer). Private practice, Recife, Brazil. Retrospective comparative study. Cataract patients who had biometric measurements with the new biometer and the reference biometer were included in the study. Comparisons were performed for axial length (AL), keratometry (K), anterior chamber depth (ACD), and IOL power calculation to reach emmetropia with an Acrysof SN60WF IOL using the Haigis formula. The Pearson correlation coefficient and the 95% limits of agreement (LoA) were calculated. The paired Student t test and the Wilcoxon test were used to assess differences between devices. Eighty-eight eyes (88 patients) were studied. Both biometers provided statistically similar mean IOL power to reach emmetropia, AL, keratometry, and ACD measurements (P > .05). The differences in these variables did not vary as their mean values increased, and there was a strong positive correlation between the values obtained by both devices for each variable. The 95% LoA values for AL, mean keratometry, ACD, and IOL power were 0.27 mm, 1.08 diopters (D), 0.66 mm, and 1.56 D, respectively. The 2 devices were comparable with regard to mean IOL power, mean AL, K, and ACD measurements. However, the wide range of differences between the devices suggests they should not be used interchangeably.