Realtors have had amazing success in keeping their commissions up. Whether you sell your house through a chain operation or an independent office, everyone in a given city will probably charge the same. Typically, you pay 6 percent. Now, however, the real estate business is moving toward the Web. Will that break the commission cartel, or not?

Over the years, many new players have entered the realty game. “But they wanted to join the cartel, not compete with it,” says John Reed, editor of the Real Estate Investor’s Monthly in Alamo, Calif.

Not that commissions are rigidly fixed. A Realtor may offer a discount to win a particular client, or cut the commission to help a buyer and seller close a deal. But that doesn’t impinge on the industry’s listed price.

New types of Realtors on the Web are advertising transactions for less. Two of them have national reach: zipRealty.com and eRealty.com. But their impact remains to be seen.

ERealty came under attack in Austin, Texas by the Board of Realtors, which represents all the Realtors in the area. The board tried to put eRealty out of business by denying it access to local real estate listings. ERealty won the first round in court, and the board is backing off.

Web Realtors can cut your costs in a couple of ways. First, they make more efficient use of something called the Multiple Listing Service (MLS).

Virtually every city has an MLS, managed by its Board of Realtors. When a Realtor gets a new property to sell, he or she usually lists it on the MLS, where everyone in the business can see it.

If the firm that got the original listing also sells the house, it will collect the full 6 percent commission. If the house is sold by a broker from another firm, the commission is split: 3 percent for the listing broker, 3 percent for the selling broker.

Increasingly, Realtors are giving the public limited access to the MLS, through local boards of Realtors, individual Realtor Web sites and Realtor.com, a venture partly owned by the National Association of Realtors, an industry group.

Shoppers using these sites can set the parameters they want zip code, school district, number of bedrooms, price range. The screen will show you still pictures of some plausible homes, and maybe a video tour.

Web tours save both the Realtor and you a lot of time. When you enter the office, you have already weeded out the less interesting homes.

Traditionally, brokers have put only their own, limited listings on their Web sites. They might offer a link to the whole MLS, through the local Board of Realtors. But even then, you might not see everything that’s for sale. Furthermore, the addresses of the houses might be suppressed, so you couldn’t drive by them yourself.

That’s where the new Web Realtors come in. They give you free access to virtually all the houses listed on the MLS in a particular city, including pictures and the address. Any questions you have can be answered by e-mail or phone.

If you want to view a property, the Web Realtor puts you in touch with its local agent. The agent might work out of his or her home, for a salary or flat fee.

If you want to buy, the local agent or an online agent will help with the price negotiation and home inspection. There’s online access to financing and insurance. If you want to sell, the Web Realtor will list your house on the MLS. The local agent handles the showings and other details.

That’s the second way Web Realtors cut their costs. They typically have no bricks-and-mortar offices. The transaction is mostly handled online, with the savings passed on to you.

ERealty.com currently operates in 11 cities. If you sell your house through the site, you pay a commission of only 4.5 percent. That’s 1.5 percent less than traditional Realtors charge.

If you buy through eRealty, the firm pays you 1 percent of the buying price (usually handled as a reduction

in closing costs). ZipRealty, now in 12 metropolitan areas, charges sellers around 4.5 percent, but gives buyers a rebate of 1.5 percent of the price.

In the end, however, I doubt that Web Realtors will break the commission cartel. On the contrary, they profit from it. They still earn half the 6 percent commission that sellers pay when using traditional Realtors.

But some consumers get a break and that’s a start.

Syndicated columnist Jane Bryant Quinn can be reached in care of the Washington Post Writers Group, 1150 15th St., Washington D.C. 20071-9200.