Bidding for a human kidney, described on the Internet auction site Ebay as ''fully functional,'' began at $25,000 and reached $5,750,100 before the company abruptly ended the auction yesterday afternoon.

In the pantheon of bizarre items that Internet users offer for sale on Ebay -- host to about 2.6 million auctions a day -- human organs are forbidden. To buy or sell them is a felony under Federal law, and trading in illegal goods is a violation of Ebay's rules.

A second kidney auction was posted yesterday afternoon starting at $4 million but had not received any bids, The Associated Press reported.

Chances are the auction, and the second posting, were jokes. But whether or not the offers were real, the incidents underscore the ease with which the Internet enables transactions of any kind, regardless of social custom or law.