San Francisco ? After years of ridicule and ruin, Internet stocks are recapturing their charm and seducing investors again.

The handsome stock market gains posted so far this year by eBay Inc., Yahoo! Inc., Amazon.com Inc. and other Internet companies have sparked a debate over whether the surge heralds a dot-com comeback or another investment bubble.

The optimists say Internet stocks are being embraced again because the once-forlorn sector is producing impressive sales growth in an otherwise lackluster economy.

Online auctioneer eBay Inc., for instance, began this year with first-quarter revenue of $476.5 million — a 94 percent increase from last year. Excluding the gains from acquisitions made during the last year, eBay’s revenue still rose by 56 percent.

That kind of growth became even more impressive as a long list of brick-and-mortar businesses disclosed depressed first-quarter revenues amid the anxieties leading up to the Iraq war.

“The Internet is the only part of the economy that’s really working right now,” said venture capitalist J. William Gurley of Benchmark Capital, which owns a stake in eBay.

Pessimists, though, say Internet companies still aren’t growing fast enough to justify their premium prices. The skeptics even question the value of San Jose, Calif.-based eBay, widely regarded as the Internet’s biggest business success.

At the end of April, eBay’s shares stood at $92.91 — a 37 percent gain since the end of 2002. The price translated into a price-to-earnings ratio of 64, based on average analyst estimates of its projected 2003 profit.

Investors commonly use the price-to-earnings, or “P/E,” ratio, to size up a company’s value. The P/E for the entire Standard & Poor’s 500 stock index is about 17, according to Thomson First Call, which compiles analyst estimates.

The disparity between eBay’s P/E and the overall market’s hasn’t scared off investors. At least nine analysts have bullish ratings for eBay’s stock.

The enthusiasm had helped lift eBay’s market value to $29.8 billion as of April 30 — more than many far larger corporate giants, including Ford Motor Co. and General Motors Corp.

The renewed fascination with Internet stocks extends beyond eBay. Through April, Yahoo’s stock had climbed by 51 percent for the year, raising its market value to $15 billion and its P/E ratio to 71. Amazon’s stock climbed 52 percent, leaving it with a P/E ratio of 61 and a market value of $11 billion — worth more than Sears, Roebuck & Co.

Some smaller Internet companies are faring even better. The stock of search engine provider Ask Jeeves Inc. had more than tripled during the first four months of the year while the shares of online DVD rental service Netflix Inc. more than doubled.

Through April, the Dow Jones Internet index was up by 25 percent for the year. That compared to gains of 2 percent for the Dow Jones industrial average, 4 percent for the Standard & Poor’s 500 and 10 percent for the tech-driven Nasdaq composite index.

The run-up suggests some investors may be getting carried away by the recent growth of Internet companies.

Even if there were a sudden sell-off in the sector, there aren’t enough Internet companies left to inflict widespread pain, said David Pottruck, co-chief executive of Charles Schwab Corp. “It’s not big enough to make a big difference any more.”

Despite the rally, most Internet stocks remain a long way from the peaks they reached during 1999 and early 2000.

Yahoo’s shares reached $237.50 in 2000 while Amazon hit $113 in 1999.

The recent rise of Internet stocks may seem stunning, given how badly investors got burned by the downfall of the past three years.

But many veterans of the high-tech industry have been predicting Internet businesses would flourish again. These expectations are largely based on what’s happened in other industries driven by revolutionary breakthroughs.

Marc Andreessen, co-founder of Web browser pioneer Netscape Communications, draws a parallel to the mid-1980s, when a boom in personal computers began to fizzle.

Some market pundits declared an end to the PC’s glory days. Those gloomy statements look silly now, given the dazzling — and enriching successes — of companies like Microsoft Corp., Intel Corp. and Dell Computer that, in retrospect, were built on the rubble of an initial investment bubble.

“We are going through almost exactly the same curve with the Internet,” Andreessen said.

For those who believe the Internet is in the early stages of an economic renaissance, it makes perfect sense to buy stock in the dot-com survivors.

“People are starting to realize that there are technologies and businesses enabled by the Internet that weren’t possible before,” said Marc Benioff, chief executive of Salesforce.com, a privately held company that may test Wall Street’s appetite for dot-coms later this year.

The potential for a long run of growth makes it difficult to appraise the value of Internet companies, said David Kathman, a fund analyst for Morningstar.

“It’s possible we could be looking back 10 years from now and saying, ‘Oh God, eBay sure was cheap back then,’ ” Kathman said.