Local governments in the Washington area and across the country are considering offering residents a new way to cut burgeoning prescription drug costs: free discount cards similar to grocery store club cards carried on a key chain.

Fairfax, Arlington, Prince George's and Howard counties and the District are considering whether to sign on to a National Association of Counties program that would cost taxpayers nothing and save cardholders an average of 19 percent when they get their prescriptions filled at CVS, Rite Aid, Walgreens and other participating pharmacies.

No forms are required. A customer would present the card at a pharmacy to receive an instant discount. The pharmacy would then pay a fee to the private company supplying the cards for the program.

Last year, 17 counties nationwide, including Montgomery County, signed up for the pilot year. Montgomery mailed cards to 200,000 households in December. To date, cardholders there have saved more than $500,000, county officials said. About 25 more counties, including Baltimore County, have signed up, and 200 are considering it.

The program is aimed at the uninsured, but participating counties have been mailing the cards to all residents. Most people who have drug coverage through their insurance plans probably would stick with their co-payment, which probably would be a better bargain, said Tom Goodman, a spokesman for the counties group, which is based in the District.

"This is the kind of program that really fills a gap that some people experience," Goodman said. "If a person doesn't have prescription drug coverage, this would save them about $12 a prescription. If they already have a plan, then this is not for them."

In Fairfax, one of the wealthiest areas in the country, about 90,000 people are uninsured, county officials said.

That makes the program seem like a "no-brainer," said Supervisor Gerald W. Hyland (D-Mount Vernon), who introduced the prescription card program at a recent county board meeting.

But some analysts said it could be a confusing addition to the flurry of discount cards issued in the past few years. In addition to the drug and grocery store club cards that customers can swipe at the checkout to get discounts on certain items, some pharmaceutical companies have begun distributing their own discount cards. And under the Medicare prescription drug bill passed two years ago, many private companies offer cards as well.

"There's just hundreds of these cards out there that are coming from a variety of sources," said Sharon A. Treat, executive director of the National Legislative Association on Prescription Drug Prices, a Maine-based nonprofit group founded by state legislators who sought to reduce drug prices. "There's different rules for each of these cards, and taking five drugs through five different programs is extremely common."

Different cards could result in more -- or less -- savings depending on the situation, and no single card can make up for the exploding cost of prescription drugs in the United States, said David Gross, a senior policy analyst for AARP.

"Twenty percent is probably a drop in the bucket for people, but it's something," he said of the estimated savings under the county program. "It's not going to bring prices down to Canadian levels or what people pay with insurance."

One advantage of the county card is that it covers medications excluded by some insurance companies, such as birth control, sex-change hormones, hair-loss pills and smoking cessation treatments.

Hyland said every little bit helps.

"There's no financial remuneration to the National Association of Counties or the county, so what is the harm to give our consumers in Fairfax a way to save money?" he asked.

Fairfax County Executive Anthony H. Griffin is reviewing the contract and developing a recommendation for the Board of Supervisors to consider at an upcoming meeting.

The National Association of Counties program began last summer in conjunction with Caremark, a Nashville-based pharmacy benefit manager that is supplying the association with a virtually unlimited number of the cards. Caremark gets a fee from the participating pharmacies for each prescription filled. The pharmacies in turn benefit from the marketing and potential influx of new customers, officials said.

Supervisor Gerald W. Hyland proposed the cards for Fairfax.