AIMS--The first 662 cases of a multicentre randomised clinical trial of intracapsular cataract extraction (ICCE) with and without implantation of a four point multiflex (Cilco Kelman Choyce Modification) anterior chamber intraocular lens (AC IOL) were studied after 6 weeks to compare frequency of surgical complications, short term clinical outcomes, and corneal endothelial cell loss between groups. METHODS--Randomisation was performed after screening for predetermined inclusion and exclusion criteria. Demographics, visual acuities, intraocular pressures, and corneal endothelium cell data were recorded preoperatively and at 6 weeks. Details of surgical procedure, complications, and postoperative adverse reactions were recorded. Monitoring of the study was secured by a standardised image documentation procedure on all patients using the IMAGEnet digital imaging system. Analysis of corneal endothelial cell images was done using the CELL SOFT software analysis program. RESULTS--343 patients were randomised to IOL and 319 to no IOL. Twelve IOL implantations (3.5%) were aborted because of complications. A complication was reported in 103 (15.6%) of the surgical procedures (IOL = 16.9%, no IOL = 14.1%, p = 0.37). The most frequent complication observed was vitreous loss followed by plain capsular rupture, unplanned ECCE, and iris dialysis. Mean corneal endothelial cell loss 6 weeks after surgery was 17.2% (SD 13.1%) in the total study population (IOL = 18.5% no IOL = 16.1%, p = 0.05). The postoperative complications registered until 6 week follow up were significantly higher in the IOL group (IOL = 6.9%, no IOL = 2.6%, p = 0.02), mainly due to mild to moderate iritis needing prolonged use of steroids. Eighty nine per cent of the patients had a best corrected visual acuity of 6/18 or better. There was no significant difference in visual outcome between study groups. CONCLUSIONS--The implantation of a multiflex AC IOL in primary ICCE surgery in the centres of this study did not increase the risk of surgical complications or short term sight threatening adverse clinical outcomes compared with ICCE without lens. Comparisons of corneal endothelial cell loss after 6 weeks between study groups showed no clinically significant difference. The difference in mean cell loss between groups was statistically significant.