THE CLINTON administration chose its target carefully when it announced an initiative to regulate fly-by-night sales of prescription drugs on the Internet. While there's been general (and not unreasonable) reluctance to slap regulatory burdens on the still developing field of electronic commerce, online drug sales are one of those Internet conveniences that can truly benefit customers only if those customers also can count on a measure of protection from the accompanying dangers. The cautious approval with which even large players in the online pharmacy field have greeted the proposal reflects broad acceptance of this point.

Plenty of reputable pharmacies have opened "branches" in cyberspace, making it possible for patients to get their prescription drugs without leaving the house -- an obvious benefit, especially to the elderly or infirm. Other companies are entirely cyber-based but still adhere to state regulations and good pharmaceutical practice, filling prescriptions only after verifying by phone, fax or other means that the patient has seen a doctor and that the medication prescribed has been checked for side effects and interactions with other medications.

But other Web sites -- estimates range as high as 400 -- follow none of these practices and are doing a brisk business in inadequately screened drugs, often "lifestyle" drugs such as Viagra or weight-loss remedies. Some are offshore, which makes direct regulation impossible. But even those within the United States are straining the traditional state-by-state licensing system for pharmacies, since patient, prescriber and dispenser may all be in different jurisdictions.

The administration's plan, if done properly, would lay only a light hand atop this state network. The Food and Drug Administration would require all sites dispensing prescription drugs to certify that they are in compliance with existing state law and to display a seal. Consumer education efforts would seek to teach people about the danger of shopping at sites without seals. (Some offshore sites sell expired drugs or those not cleared for use in the United States; others that don't require a doctor's involvement in prescribing have been implicated in bad reactions.)

Congress, which must approve the plan, has sent skeptical signals, but at least one key Republican -- Rep. Billy Tauzin (La.) -- has indicated he would work with the administration on the legislation, which would likely come before his subcommittee. Any such law needs to have sufficient teeth to give consumers confidence, if online pharmacies are to flourish. It's hard to find many partisans for the unregulated practice of medicine, online or off.