Decrease of intraocular pressure (IOP) and the occurrence of cataract were analysed in 75 patients of a community-based material followed for 6-12 years after trabeculectomy. IOP was controlled (less than or equal to 21 mmHg) with or without additional treatment in approximately 90% of the eyes, both at 5 years and at the last visit. The share of eyes requiring no medication for IOP control decreased linearly with time from approximately 90 to 60% between one and 10 years postoperatively. Thirty-eight per cent of the patients without cataract at the time of operation suffered from cataract development during follow-up. The prevalence of dense cataract producing severe visual loss at the last visit was 47%. The occurrence of cataract was correlated with the age of patients at operation. Cataract formation showed no relationship of statistical significance with preoperative treatment, with time since surgery, the magnitude of preoperative IOP and the reduction of postoperative IOP.