OBJECTIVES: To determine the impact of differences in care and services provided to the visually impaired in the United Kingdom (UK) and the United States (US) on the cost-effectiveness of pegaptanib in age-related macular degeneration (ARMD). MEHTODS: A Markov model was used to model the visual acuity of a cohort of ARMD patients over a period of 10 years. Country-specific data for the US and UK included mortality rates, treatment-related costs, adverse event treatment patterns, costs associated with excess cases of depression and injury, and services provided to the visually impaired. In the UK, these consisted of visual aids and rehabilitation, community and residential care, and social security benefits. In the US, these included all Medicare costs including skilled nursing facility and nursing home care. Social security benefits have not been quantified in the US and could not be included. RESULTS: The incremental benefit of pegaptanib was slightly higher in the US than the UK due to the slightly greater life expectancy (incremental quality-adjusted life year [QALY] estimates were 0.302 and 0.297, respectively). The average per patient cost associated with the provision of services to those with visual impairment was similar when social security benefits were excluded but substantially lower in the US than the UK when they were included ($24,815 and GBP 25,014 [~$46,326] per patient receiving standard care, respectively). This resulted in higher incremental cost/QALY estimates in the US than the UK ($37,607 and GBP 8,023 [~$14,842], respectively). CONCLUSION: Pegaptanib is expected to be cost-effective at recognized thresholds in both healthcare systems, despite differences in the provision of health and personal care. Cost-effectiveness in the US may be underestimated due to the lack of information on the cost of social security benefits for the visually impaired.