In a prospective study of 351 consecutive cataract operations performed on Finnish patients, the prevalence of exfoliation syndrome was 31% (108 of 351 eyes), increasing from 0% (zero of 54 eyes) in patients younger than 60 years to 15% (12 of 78 eyes) in patients aged 60 to 69 years, 42% (57 of 137 eyes) in patients aged 70 to 79 years, and 48% (39 of 82 eyes) in those aged 80 years or more, than has previously been reported in general populations of the same age in Finland. Exfoliation syndrome was more common in patients aged 70 years or more. Glaucoma was found in 41 of 108 eyes with exfoliation syndrome (38%). Exfoliation syndrome increased the risk of intraoperative complications in extracapsular cataract extraction either directly (rupture of the zonules) or through poor dilation of the pupil (rupture of the posterior lens capsule). The occurrence of vitreous loss was fourfold, and the need to use an anterior chamber intraocular lens instead of a posterior chamber lens because of loss of capsular support was tenfold in eyes with exfoliation as compared to those without exfoliation.