The line between full-service brokers and online brokers might as well be in invisible ink.

DLJdirect

(DIR)

, the online unit of

Donaldson Lufkin & Jenrette

(DLJ)

, on Friday said it would open branch offices, starting with a Boca Raton, Fla., location on Monday.

DLJdirect's move to "bricks and clicks" shouldn't have surprised anyone -- other online brokers such as

E*Trade

(EGRP)

and

Web Street Securities

(WEBS)

also have decided to do the branch thing this year.

But the move could mean that online brokerages not opening branches are now going to find themselves as a very small group. Indeed, of the top 10 online brokers, only

Ameritrade

(AMTD) - Get Report

and

Datek Online

have no branches. Datek says it's considering opening branches in a limited way. An Ameritrade spokeswoman said the broker isn't planning to open branches, but she couldn't say why.

For DLJdirect, the move to branches could signal a first step toward a more broad-based product line and financial advice, following industry leader

Charles Schwab

(SCH)

. And that, in turn, could help its stock, says Richard Repetto, an analyst at

Lehman Brothers

, which hasn't done underwriting for DLJdirect.

The stocks of Schwab and online broker

TD Waterhouse

(TWE)

have outpaced their online brethren this year in part because they aren't so dependent on commissions. Schwab's stock, for instance, is up about 16% this year, while DLJdirect's has tumbled 20%.

"I just think it's a good idea in general for the online brokerages," says Greg Smith, an analyst at

Chase H&Q

. "The pendulum always swings too far in both directions. Just as

Merrill Lynch

(MER)

has resisted online trading, online brokers have resisted bricks and mortar. At the end of the day, it's not very expensive to selectively open a few branches."

Brokers say that customers like to use the branches to open accounts and deposit checks even though those services are also available online. And it's a relatively cheap way to advertise services. Schwab, which opened its doors in 1975, stuck by its branch strategy even as its online trading business exploded in the late '90s. The combination worked, turning it into the biggest online broker.

In fact, Schwab's success in attracting full-service accounts pushed Merrill and other brokers to begin offering online trading last year to their full-service customers, including popular fee-based wrap accounts that allow unlimited trading in exchange for a fee based on assets.

Blake Darcy, DLJdirect's CEO, says the days of the pure-play online brokerage are gone. And he's been in the online trading business since the days of dial-up systems 11 years ago.

"Now you're going to compete head-to-head against bricks-and-mortar securities firms," Darcy says. "We're really not going to fight history here. We are going to, in our first attempt here, try to model a cost-effective branch in the right kind of location."

Depending on how the branch does, DLJdirect could open as many as 100 branches over 18 to 24 months. It will locate the branches in major cities and other areas where it has a high-asset customer base. Darcy also doesn't rule out the possibility that some day those branches would have the same kind of financial advisers that Schwab has successfully used. Schwab and rival

Fidelity

are discount brokers, but with their additional advisory services, they're aiming for traditional full-service territory.

DLJdirect is the seventh-largest online brokerage, according to a first-quarter survey by

U.S. Bancorp Piper Jaffray

, with 44,100 trades per day and market share of 3.2%. That compares with Schwab's more-than-21% market share.

Numbers like those make it clear why DLJdirect is dabbling in real estate.