We sought to prospectively document and evaluate the learning curve of an experienced extracapsular surgeon making a supervised transition from extracapsular cataract extraction (ECCE) to phacoemulsification. Over a period of 2 weeks, 51 phacoemulsification procedures using an endocapsular nucleofractis technique were performed by a single senior surgeon at the Christian Medical College in Vellore, India under the supervision of a visiting US expert with more than 15 years' experience in the technique. Vitreous loss occurred in seven eyes (six prior to the stage of cortical aspiration); failure of capsulorhexis necessitated conversion to standard ECCE in four. Injury to the inferior iris during phacoemulsification was cosmetically significant in three eyes. Two eyes had mild persistent localized corneal edema, but there were no instances of permanent corneal damage. One eye had intraoperative displacement of the nucleus into the vitreous. In one eye with vitreous loss, the implanted intraocular lens dislocated into the vitreous cavity. Two patients had clinically detectable cystoid macular edema at 6 weeks. Eleven patients were lost to follow up after 3 weeks. Six weeks after surgery, 36 of the remaining 40 eyes (90%) had achieved a best-corrected visual acuity of 6/6. We conclude that phacoemulsification requires supervised learning, even for an experienced surgeon. Complications still occurred, but were restricted to the unfamiliar steps of the surgery. Factors identified in the first 2 days of surgery (10 cases) as critical in the smooth transition to phacoemulsification were careful selection of initial cases, a successful capsulorhexis, and hydrodissection with vigorous nucleus mobilization.(ABSTRACT TRUNCATED AT 250 WORDS)