Chances are you won't end up in a nursing home. Chances are you'll be able to grow old without needing any kind of long-term institutional or professional care.

But if you are one of a small percentage of Americans who do end up needing long-term care, be prepared for a severe financial blow: Nursing homes cost, on average, $22,000 a year. Many private health insurance plans don't cover the cost, Medicare covers only a small portion of it, and the welfare system will pick up the check only if you've exhausted a share of your own savings first.The financial threat posed by long-term care isn't as serious as it once was. In the Catastrophic Health Insurance Act passed this year by Congress, there are provisions to protect families from being bankrupted by paying for nursing home costs. And attempts are under way both among insurance companies and in Congress to protect Americans from the enormous costs of paying for the disabled elderly.

Nonetheless, preparing for long-term care remains a complicated and difficult task.

The gist of the problem is that the patchwork of public and private health insurance programs in the United States has not yet been extended to cover the often catastrophic nursing home and long-term care expenses incurred by the elderly. Next to primary medical coverage or any of the other early targets of social programs, long-term care is only an issue for a relatively small number of Americans, which has made it less of a priority for lawmakers.

At present, for example, only about 5 percent of the nation's 30 million elderly are in nursing homes. Over the next 30 years that percentage is expected to grow somewhat - of the 50 million Americans over 65 in the year 2018, as many as 4 million may be in nursing homes. Other estimates are higher, suggesting that Americans over 65 have between a 40 and 50 percent chance of staying in a nursing home at some point. But the figures are somewhat misleading because the average length of most nursing home stays is very modest.

For example, 31 percent of nursing home patients stay for less than a month, 20.6 stay from one to three months, 11.2 percent from three to six months, another 11.2 percent from six months to a year, 15 percent from one to three years, and the remaining 10 percent for three years or more.

The median nursing home stay is 82 days. Only a fraction of that 5 percent actually stays long enough to run up serious bills. Most of the elderly in need of some care - at present about 15 percent of those over 65 - receive it either at home or in the community.

On top of that, the lot of those saddled with long-term care needs is about to improve dramatically. Until now, Medicare has covered only the first 20 days of a nursing home stay, a fraction of the next 80 days, and nothing after that. And Medicaid, the federal welfare system, has picked up the tab only after nursing home residents have spent all of their own assets to pay for care first.

But the catastrophic health legislation changed the rules concerning eligibility for Medicaid coverage. As of next September, Medicaid payments will kick in much earlier, allowing the spouses of nursing home residents to keep a greater portion of their own assets before qualifying for welfare assistance.

At the same time, there have been a number of serious proposals put forth in Congress that would have the federal government pick up the cost of any long-term nursing home resident, paying for either the first three years of all nursing home stays or, alternatively, any time after the first three years.

Last year the $33 billion that America spent on long-term care was split about evenly between the pockets of patients and the federal government. According to some health care experts, there is a good chance that at some point within the next decade the government will pick up an even greater share.

Given these circumstances, few consumers have even bothered to buy long-term health insurance. When Aetna Life Insurance Co. offered long-term care coverage to its own employees, only 7 percent bought it.

The lack of interest in private long-term plans has a reinforcing effect. Because only those truly in need of long-term care tend to buy private insurance, insurance companies are forced either to raise premiums to prohibitive levels or limit the coverage offered by policies in order to make the coverage profitable.

The result is that many plans offer what some health care experts say is inadequate coverage. A study released by the United Seniors Health Cooperative earlier this year estimated that long-term policies offered by 21 companies in the Washington metropolitan area would actually pay out nursing home benefits only 39 percent of the time.

One culprit is requirements that claimants be hospitalized before entering a nursing home, or that claimants first receive skilled care before receiving more standard care.

The other culprit is inflation. Many plans offered a fixed benefit, say $50 a day, which roughly corresponds to the average national cost of a day in a nursing home. But nursing home costs are rising faster than the rate of inflation, and by the year 2008, an intermediate-care facility will cost $170 a day. Unless it is adjusted for inflation, in other words, a long-term policy could be of little value when it is actually cashed in.

Still, most financial planners recommend some degree of long-term coverage in cases where the elderly have significant asset bases to protect.

A handful of life insurance firms, for example, now allow the insured to pay a very small additional premium that allows them to draw on their death benefit in the event they need nursing home care. Typically such plans allow for about half of the death benefit to be used to pay nursing home expenses, up to 2 percent of value a month.

Other companies are stressing broader-based plans that encourage Americans to start paying for long-term care insurance at an earlier age, and also attempt to lure more people into the program by covering not just nursing home care but home care as well.

By attempting to reach a wider base of insured and creating incentives for the use of less expensive home care, the plans allow for substantially lower premiums and greater benefits.