The majority of Medicare drug benefits in managed care (Medicare + Choice) have annual dollar limits or caps and many beneficiaries face temporary but potentially significant gaps in coverage after exceeding caps before the end of the year. In the new national Medicare drug benefit, beneficiaries with high medication expenditures will also face a period without drug coverage when their total drug costs exceed annual caps but are not high enough to qualify for catastrophic coverage.To describe strategies adopted by beneficiaries exceeding annual drug benefit caps to lower prescription costs, the type of medications involved, and their financial burden.A survey (completed in 2002) of Medicare + Choice beneficiaries aged 65 years and older with high medication costs and benefits capped on the plan's share of drug costs (65% response rate). The different caps offered in different counties were used as a natural experiment. Study participants (n = 665) exceeded a 750 dollars or 1200 dollars yearly cap in 2001 and had coverage gaps of 75 to 180 days. Control participants (n = 643) had 2000 dollars caps, which they did not exceed. Study and control participants were matched by average total drug expenditures per month.Proportion of beneficiaries reporting specific strategies to decrease medication costs, medications affected, and difficulty paying for prescriptions.In multivariate analyses adjusting for demographic and health characteristics, a higher proportion of patients exceeding caps reported using less prescribed medication than controls (18% vs 10%, respectively; P<.001), but similar proportions reported stopping medications completely (8% for both, P =.86) and of not starting prescribed medications (6% vs 5%, P =.39). Patients exceeding caps more often called pharmacies to find the best price (46% vs 29%, P<.001), switched medications (15% vs 9%, P =.002), used samples (34% vs 27%, P =.006), and had difficulty paying for prescriptions (62% vs 37%, P<.001). Twelve of the 20 therapeutic classes most often affected by decreases in use of medication were for chronic health problems such as hypertension, hyperlipidemia, and emphysema or asthma.Medicare beneficiaries often decreased use of essential medications and experienced difficulty paying for prescriptions during gaps in coverage. Health professionals need to explore how they can lessen the impact of caps on patients' health and financial burden.