OBJECTIVE: To compare postoperative social costs of two cataract surgical techniques, phacoemulsification (PHACO) and extracapsular extraction (ECCE). METHODS: Prospective randomized intervention study including 205 patients, of which 101 underwent PHACO and 104 ECCE in the public service, in the city of São Paulo, Southeastern Brazil, in 2002. The socioeconomic impact of these surgical procedures was assessed based on postoperative costs for patients, employers and social security. Comparisons between the two groups studied were performed using the chi-square test or Mann-Whitney test, when appropriate. A 5% significance level was set. RESULTS: Hospital and eyeglasses costs for PHACO were lower than for ECCE patients, with a mean difference of US$ 16.74. Costs to employers related to medical leave for the first 15 days of absence and costs of caregivers in the form of absence from work to attend postoperative follow-up visits were on average US$ 0.18 lower in PHACO compared to ECCE group. The estimated Social Security expenditure per patient undergoing surgery was US$ 6.57 and US$ 51.15 in PHACO and ECCE groups, respectively. CONCLUSIONS: The average saving with PHACO compared to ECCE technique was US$ 61.50 for employers, patients, caregivers and Social Security.