Background: It has been estimated that 67 million people worldwide are affected with a primary glaucoma and that one-third have primary angle closure glaucoma. We aimed to determine the biometric differences between the eyes of patients with acute attack of primary angle closure and their non-involved fellow eyes. Methods: Twenty eight patients with acute attack of primary angle closure were recruited in this prospective study. Three weeks after laser iridotomy and resolution of corneal edema, all patients had a complete ocular examination including slit lamp biomicroscopy, pachymetry, keratometry, and ocular biometry. The following A-scan parameters were measured: anterior chamber depth, lens thickness, axial length, lens– axial length factor, relative lens position, and corrected anterior chamber depth. Results: There were 22 (78.5%) women and six (21.5%) men with mean age of 52.82±9.25 years. There were no statistically significant differences in the biometric figures between the affected and fellow eyes [anterior chamber depth (P=0.4), lens thickness (P=0.4), axial length (P=0.7), lens-axial length factor (P=0.6), relative lens position (P=0.7), and corrected anterior chamber depth (P=0.8)]. The mean ± standard deviation of central corneal thickness in the affected and fellow eyes were 560.12±41.93 and 557.727±18.53, respectively (P=0.806). There was no statistically significant difference between the both eyes in the mean keratometric diopters in the affected and in the fellow eyes (45.05±2.02 v 44.91±1.73; P=0.78). Conclusion: The present study did not reveal any statistically significant differences regarding the ocular biometric parameters between the affected and fellow eyes in patients with acute primary angle closure. The biometric parameters were similar between male and female patients as well.