Back in the 1990s, steroids could be surreptitiously purchased out of the trunk of somebody's car. A decade ago, they could be found in dietary supplements sold on bodybuilding Internet sites.

Now, steroids are readily available through Amazon.com, according to a prominent anti-doping researcher who ordered several dietary supplements from the consumer Web site and tested them to verify that they indeed contained potent, illegal - and potentially dangerous - oral steroids.

"To me, it's absolutely an amazing story," said Don Catlin, the chief executive officer of Anti-Doping Research in Los Angeles. "To just go on Amazon.com and order anabolic steroids."

Catlin and his son Oliver Catlin, the company's vice president and chief financial officer, have notified the Web site and officials from the Drug Enforcement Administration and Food and Drug Administration, and they revealed their findings Tuesday.

The Catlins say they purchased eight to 10 products that purported to be legal, muscle-building dietary supplements through Amazon.com in recent months and have completed analyses on four of them. Three of the four tested so far have contained significant quantities of steroids.

The Catlins' work suggests that it remains easier than ever to obtain powerful steroids, despite a tightening of the nation's steroid laws in 2004 and various efforts by the FDA to crack down on manufacturers who illegally put steroids in dietary supplements.

"These things shouldn't be sitting at people's fingertips," Oliver Catlin said. "They certainly shouldn't be at the fingertips of high school students and so forth, and they are there available to anyone."

Amazon did not immediately return a request for comment.

None of the eight to 10 products the Catlins obtained was subject to age or other ordering restrictions from Amazon.com, and the Web site did not provide health warnings of any kind. The Catlins said the products can cause severe liver damage as well as other side effects, and none was medical-grade pure when tested, suggesting that other trouble could result from ingestion.

Each was purchased through a different seller, with only one product shipped directly from Amazon's warehouse.

It is illegal to sell anabolic steroids as dietary supplements, which are supposed to contain only natural ingredients.

The Catlins found steroids known as Madol, Tren and Methasterone in Competitive Edge Labs products called P-Plex, X-Tren and M-Drol, both said. All three steroids have become popular and well-known through their appearance in various dietary supplement products in the last decade.

However, in an e-mail and a message on its Web site, www.competitiveedgelabs.com, the company claims it discontinued sales on all of those products more than a year ago. A company spokesperson also said Competitive Edge has never sold its products through Amazon.

Oliver Catlin noted that the products all had fresh expiration dates, suggesting they were recently made.

Steroids were made illegal without a prescription in the United States in the Anabolic Steroid Act of 1990. But with the loosening of restrictions on dietary supplements in 1994, some manufacturers saw supplements as an effective vehicle for steroid distribution since the FDA did not review or inspect dietary supplements before they went to market. It is the manufacturer's responsibility to ensure its products are legal and safe.

"We have been doing surveillance on these types of products for many years," said Siobhan DeLancey, an FDA spokeswoman. "We're dealing with people who are really operating outside the law. . . . They don't have a real incentive to comply with our regulations. They are just trying to move products."

Don Catlin identified Madol and Methasterone in dietary supplements he analyzed at The Washington Post's request in 2005; Catlin's work at that time spurred FDA action against the companies and legislation making Madol illegal without a prescription, but the steroids themselves remained popular and continued to be designed and sold.

"There's a million other products on sale on Amazon that are similar" to the ones we analyzed, Oliver Catlin said. "It's an easy place to shop and look for these things. They remain widely available."