BACKGROUND A near-total shift to cataract extraction on an outpatient basis occurred as a result of an administrative ruling by the Health Care Financing Administration. No national study has been conducted to assess the possible effects of that decision on clinical outcomes of surgery. The authors compared the rates of retinal detachment (RD) repair and hospitalization for endophthalmitis after extracapsular cataract extraction (ECCE) (including phacoemulsification) in 1986 and 1987 with those following inpatient cataract extraction in 1984. METHODS Using the 5% random sample of Medicare beneficiaries, we analyzed the claims of all individuals 66 years of age or older who underwent ECCE by nuclear expression or phacoemulsification in 1986 and 1987. A total of 57,103 patients were identified and followed to the end of 1988. Cumulative probability of RD repair and hospitalization for endophthalmitis was calculated by standard lifetable methods. These findings were compared with the cumulative probability of the same complications in a cohort of 330,000 patients who underwent cataract extraction on an inpatient basis in 1984. RESULTS In the 1986-to-1987 cohort, the cumulative probability of RD within 3 years after cataract surgery was 0.81% and the cumulative probability of endophthalmitis within 1 year was 0.08%. The rate of RD is similar to that which we previously reported for 330,000 patients who underwent inpatient surgery in 1984, but the rate of endophthalmitis is significantly lower in the 1986-to-1987 outpatient cohort (0.08% versus 0.12%; z = 2.42; P = 0.01). CONCLUSIONS The shift to outpatient cataract surgery was accompanied by no significant increase in the probability of RD repair and possibly a significant decrease in the rate of hospitalization for endophthalmitis.