This study assessed corneal endothelial damage in endocapsular phacoemulsification surgery using a nuclear cracking procedure in which the nucleus was divided into four quadrants and emulsified. Forty-five eyes had phacoemulsification using this technique, and 33 eyes had phacoemulsification using undivided sculpting techniques (without cracking). We examined the extent of endothelial cell loss at one and three months after surgery using specular microscopy. We also measured ultrasound time, time spent for phacoemulsification, and infusion volume during surgery. Endothelial cell loss was significantly less in the nuclear cracking group than in the undivided sculpting group. Ultrasound time in surgery with cracking was significantly shorter than that in surgery without cracking. The time for the phacoemulsification maneuvers and the infusion volume were the same for both procedures. These findings indicate that the ultrasound time was shortened using the nuclear cracking technique and resulted in less corneal injury.