Background: Implantation of an intraocular lens (IOL) is the gold standard in modern-day cataract surgery. Over the last decade, IOL power calculations have become a focal point of cataract surgery. Objective: To compare the sensitivity and specification of optical biometry and applanation ultrasound biometry in the measurement of intraocular lens. Patient and methods: This prospective cohort study was done on 100 eyes from one hundred patients undergoing phacoemulsification with primary intraocular lens implantation. and scheduled for cataract surgery in the Ophthalmology Department of Menoufia University Hospitals and El-Mahalla Ophthalmology Hospital. Fifty eyes of patients were measured by ultrasound measurement (by A-Scan, Group 1) and the other 50 eyes by optical biometry (by IOL Master, Group 2). Result: in Group 1There were 22 eyes of 22males (44%), and 28 eyes of 28 females (56%) with a mean age was 58.4 ±10.13years. While, in Group 2, there were 16 eyes of 16 males (32%), and 34 eyes of thirty-fourth females (68%) and the mean age of the patients in this group was 61.2±9.25 years. The mean IOL of the patient in Group I was (18.86±2.57) with minimum IOL power (16.29) and maximum IOL power (21.43). Whereas, the mean IOL potent ion of the patient in group II was (20.5±1.98) with minimum IOL power (18.52) and maximum IOL power (+22.48). Conclusion: We can conclude that IOL measurements performed by using the Zeiss IOL Master, using partial coherence interferometry, resulted that a significantly better IOL power forecast and therefore the refractive result in cataract surgery than Applanation US biometry.