The plans enjoyed the strong support of President George Bush in the election campaign and have seen a small but growing number of employers offering them, says Jon Gabel, vice president of health systems studies at the Health Research and Educational Trust.
Between 1.5 and 2 million Americans now use the health savings accounts, which were passed by Congress last year.
John Bertko, the chief actuary at the Humana insurance company, says the plans may have cut costs by as much as 5% among 100,000 customers who've used them this year. Bertko calls the figure "speculative," noting that it is too early to tell if the accounts can save money while maintaining quality or if consumers will even use them.
Others agree. "We should probably wait a little while before we decide if they're working or not," says Gary Claxton, vice president of the Kaiser Family Foundation.