OBJECTIVE: To assess the relative cost-effectiveness of monotherapy with latanoprost or timolol in the treatment of open-angle glaucoma in Denmark, Norway, Sweden (Scandinavia), and the United Kingdom (UK). METHODS: Cost-effectiveness analysis was performed using a Markov model. The health states were stable and progressed glaucoma. Transition probabilities for primary open-angle and exfoliation glaucoma were derived from the medical literature, and data concerning practice patterns were obtained from surveys completed by 54 ophthalmologists geographically dispersed throughout each of the countries. Country-specific unit costs were assigned for medications, patient visits, diagnostics, and therapeutic procedures. Quality of life weights for various levels of visual acuity ranged from 0.50 to 0.68. A payer perspective with a 5-year time horizon was adopted and costs were discounted at 3% for Scandinavia or 3.5% for the UK per year. RESULTS: Latanoprost was less expensive than timolol, ranging from 5.4% to 6.7% less in Scandinavia and by 2.1% less in the UK. The range of effectiveness (years to progression of glaucoma) between treatment cohorts was narrow, from 0.003 to 0.01, which may have reflected the fact that the design assumed that physicians control most patients' glaucoma over 5 years by adding or changing therapy. Incremental cost-effectiveness ratios for latanoprost versus timolol were DKK 447,857 in Denmark, NOK 457,212 in Norway, SEK 1,251,126 in Sweden, and GBP 6,087 in the UK. CONCLUSIONS: Over a 5-year period, latanoprost monotherapy is as cost-effective as traditional timolol generics in Scandinavia and the UK.