A prospective study for evaluation of the pseudoexfoliation syndrome (PES) as a risk factor in extracapsular surgery was undertaken from February 1986 to June 1988. The study included 2042 planned extracapsular cataract extractions performed by 12 surgeons. Seventy-two eyes revealed PES (3.5%). Frequency of PES increased with age (p less than 0.005). The male-female ratio of PES was 1:1.6, and eyes of average axial length showed PES more frequently than myopic or hyperopic eyes, although these differences were not significant statistically. The incidence of vitreous loss was 11.1% in eyes with PES and 1.6% in eyes without PES, a sevenfold increase that was statistically significant (p less than 0.0001). Rupture of the posterior lens capsule was observed in 4.2% of PES eyes compared to 2.8% of eyes without PES (no significance). The pseudoexfoliation syndrome is not a harmless anomaly, but a potentially disastrous disease of the anterior segment of the eye. As precautionary measures we recommend thorough biomicroscopic examination preoperatively for signs of PES, iridotomy or sector iridectomy in cases with poorly dilating pupils, very gentle manipulation intraoperatively, and posterior chamber lens sulcus implantation in eyes with zonular defects or phacodonesis.