Twenty-seven percent of boomers surveyed in August said they were "indifferent" about enrolling in Medicare, while 26% said they were "nervous" and 14% said they were "overwhelmed."

The report, released Monday by the National Council on Aging, found that 35% of boomers don't understand the program while 16% said they didn't understand it at all.

Almost half of boomers haven't shopped for cheaper health care coverage than what they can get through Medicare, the survey, conducted by Gfk Roper for the NCOA and United Healthcare, found. The NCOA announced Monday that 41% of those seniors hadn't shopped around because they didn't believe they could save any money. However, 59% of those who hadn't shopped around for new coverage said they hadn't done so because they are satisfied with their current coverage.