AIM: To evaluate the cost-effectiveness of first eye cataract surgery compared with no surgery from a health service and personal social services perspective. METHODS: An economic evaluation undertaken alongside a randomised controlled trial of first eye cataract surgery in secondary care ophthalmology clinics. A sample of 306 women over 70 years old with bilateral cataracts was randomised to cataract surgery (expedited, approximately four weeks) or control (routine, 12 months wait); 75% of participants had baseline acuity of 6/12 or better. Outcomes included falls and the EuroQol EQ-5D. RESULTS: The operated group cost a mean pounds sterling 2004 (bootstrapped) more than the control group over one year (95% confidence interval (CI), pounds sterling 1363 to pounds sterling 2833) (p>0.001), but experienced on average 0.456 fewer falls, an incremental cost per fall prevented of pounds sterling 4390. The bootstrapped mean gain in quality adjusted life years (QALYs) per patient was 0.056 (95% CI, 0.006 to 0.108) (p>0.001). The incremental cost-utility ratio was pounds sterling 35 704, above the currently accepted UK threshold level of willingness to pay per QALY of pounds sterling 30 000. However, in an analysis modelling costs and benefits over patients' expected lifetime, the incremental cost per QALY was pounds sterling 13 172, under conservative assumptions. CONCLUSIONS: First eye cataract surgery, while cost-ineffective over the trial period, was probably cost-effective over the participants' remaining lifetime.