ATLANTA (AP) _ Coca-Cola has been pushing diet Coke just for the taste of it for years, but now that Diet Pepsi's got the right one, baby, Coke's slogan may be headed for a tune-up.

The soft-drink makers are keeping the cola wars alive in the industry's fast-growing diet segment by trying to beat each other at the advertising game.

Diet Pepsi's ''You got the right one baby, uh-huh 3/8'' campaign, featuring soul music legend Ray Charles, has grabbed the lion's share of attention this year, spawning a series of self-parodying follow-up ads by Pepsi and even a line of T-shirts.

Diet Coke has stuck with the ''Just for the taste of it'' slogan it has used for nine years as the brand has risen to the third-best selling soft drink in the nation.

Randy Donaldson, spokesman for The Coca-Cola Co. in Atlanta, said Wednesday the company was considering some changes in its diet Coke ads, but the foundation of the campaign would remain the slogan that has been in place since the drink's 1982 introduction.

'''Just for the taste of it' will continue,'' he said.

Donaldson said the company is looking at changes that would ''give a new fresh twist to the advertising, like we do every year.''

Donaldson said Coca-Cola would not be influenced by the competition's ads. He claimed Charles, who hawked Coke in the 1960s, has not helped No. 4 Diet Pepsi cut into diet Coke's market share.

''I would argue that point'' that the Charles ads have been successful, Donaldson said. ''It has gotten a lot of attention.''

Diet Coke had a 9.3 percent market share, up 0.5 percentage points from the previous year, and Diet Pepsi had a 6.3 percent share, up 0.3 percent, according to the 1990 rankings of Beverage Digest, an industry publication.

Pepsi Cola officials are positively ecstatic over the Diet Pepsi campaign, which was launched in January.

''It's been a smashing success for us,'' said Pepsi spokesman Andrew Giangola. ''The slogan itself, we think of it as a phrase that has really entered the pop lexicon.''

Giangola said the Purchase, N.Y.-based company is beginning to put the ''Uh-huh'' slogan on Diet Pepsi cans. A new commercial, now in the works, will feature the winners of a national amateur video ''Uh-huh'' contest.

Donaldson declined to discuss specific changes being considered for the diet Coke ads, and he dismissed media suggestions that the ''Just for the taste of it'' slogan itself would be altered.

Emanuel Goldman, a soft-drink industry analyst for Paine Webber Inc. in San Francisco, said it would not be unusual for Coke to tinker with the ads.

''The company that does not continually evaluate and re-evaluate is a company whose ads will ultimately fail,'' Goldman said. ''I think all of advertising is continuously going through that process.''

The success of ads by one company does not go unnoticed by the other, Goldman added. That alone does not warrant a change, though.

''They're always looking at each other. You know it and I know it, no matter what they say,'' he said. ''But if you come up with something good, you're not going to let the competition sidetrack you.''

Advertising for diet Coke has always stressed its taste rather than its low-calorie content, though recent ads have had different music and incorporated new themes on the basic slogan. Singer Paula Abdul is featured in the current television spots for diet Coke.

The diet Coke slogan is an example of ''a strategy that should last many, many years,'' said Kenneth L. Bernhardt, a marketing professor at Georgia State University.

''Whether they say the exact words or update it is not the issue,'' he said.