PURPOSE: To compare the anterior segment parameters of myopic, hyperopic, and emmetropic children by using optical biometry. METHODS: This prospective cross-sectional study included 150 eyes of 150 children between 6 and 16 years old. The eyes were divided into three groups according to their spherical equivalent (SE) refractive error values as myopic [between - 1.0 and - 6.0 diopter (D)], emmetropic (between + 0.50 and - 0.50 D), and hyperopic (between + 1. 0 and + 3.0 D). Axial length (AL), central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), and mean keratometry (K mean) measurements were obtained by an optical biometry (LenStar LS 900, Haag Streit Diagnostics) were compared between the groups. RESULTS: There were no statistically significant differences regarding the ages and genders of the participants between the groups (p > 0.05). The mean SE refractive error values were - 2.20 ± 0.71 D in myopic, - 0.08 ± 0.49 D in emmetropic, and + 2.06 ± 0.53 D in hyperopic eyes. The mean AL values were 24.50 ± 0.69, 23.41 ± 0.61, and 22.33 ± 0.61 mm, respectively, in myopic, emmetropic, and hyperopic eyes (p < 0.001). The mean ACD values were 3.94 ± 0.22, 3.78 ± 0.23, and 3.45 ± 0.20 mm, respectively, in myopic, emmetropic, and hyperopic eyes (p < 0.001). The mean LT values were 3.56 ± 0.20, 3.43 ± 0.17, and 3.31 ± 0.12 mm, respectively, in myopic, emmetropic, and hyperopic eyes (p < 0.001). There were no significant differences in the other parameters between the groups. CONCLUSIONS: Refractive errors are the main factors those affect anterior segment parameters and AL in children and the most severely affected parameters were found to be the AL, ACD, and LT values.