Improved by both technology and new surgical procedures, phacoemulsification of the nucleus has become increasingly important in extracapsular cataract surgery. Phacoemulsification within the capsular bag has proved to be a valuable surgical technique, yielding predominantly good results. In the hands of a carefully trained, critical surgeon, this procedure results in safe in-the-bag fixation of an intraocular lens. In intravitreal surgery it is almost indispensable. In special cases, such as congenital coloboma, hydrophthalmia in adults, pseudoexfoliation syndrome, risk of expulsive hemorrhage, or in cataract surgery following penetrating keratoplasty, phacoemulsification of the nucleus may be surgically safer than expression of the nucleus through a large corneoscleral incision.