Background: Cataract is the most prevalent ophthalmic cause of reversible blindness and it is one of the primary concerns of the public health perspective surgery which is the primary and only treatment method known. Objective: Assessment of corneal endothelial changes by using specular microscopy, after uncomplicated phacoemulsification in moderately hard nuclear 3 senile cataract. Patients and Methods: The present study was performed on 30 eyes of 30 individuals preoperative assessed by pentacam to detect grade 3 nuclear cataract to be selected in our study, then corneal endothelium assessed by specular microscopy to evaluate the corneal endothelium to be reference and to be compared to 1st and 3 rd month. Results: A highly significant decrease in ECD 1st month post-operative and a significant decrease in ECD 3rd month in relation to pre-operative state. Highly significant increase in the coefficient of variation 1st month postoperative and non-significant increase in the 3rd month in relation to preoperative state. Highly significant decrease in the percentage of hexagonality 1st month and 3rd month post operatively. There is a highly significant reciprocal correlation between age and pre-operative endothelial cell density. 3rd month post-operative decrease in ECD is significant correlated to male sex. Conclusion: A major finding of our manuscript is that the harder the senile cataract the more time and surgical manipulation was done in spite of the same surgeon and the same operative condition lead to more endothelium lost and the more variation between the cells and decrease in the percentage of hexagonal post-operative.