Lights, camera, action! The boss is on the air

''Step right up, step right up, lay-deeze and gen-til-mun!'' That once was the rallying cry of the carnival barker - a man of authority, sometimes dressed in a dogeared top hat and tails, but sporting a mustache of undeniable distinction. His message: Buy, buy, buy!

Today, the ''pitch'' may be more sophisticated, the medium more high-tech, and the clothes well tailored, but the message is the same. And, in a growing number of television and radio ads, the pitchmen are no longer actors. They are the chief executive officers (CEOs) of some of America's leading corporations, and they're selling cars, airline tickets, hotel rooms, ice cream, electric razors - even chickens and Cornish game hens.

Take Frank Perdue, CEO of Perdue Farms Inc. Since 1971, ''Mr. Chicken,'' as colleagues and competitors alike call him, has made more than 100 TV commercials for his company.

''It takes a tough man to make a tender chicken,'' say many ads featuring the folksy chicken magnate. Perdue Farms spokesmen say their boss's appearances have played a major role in the company's spectacular growth. In 1971, the company sold 750,000 chickens a week; today it sells more than 5 million a week.

Lee Iacocca, CEO of Chrysler Corporation, is something of a reluctant pitchman. In fact, he tells reporters he doesn't want to do commercials. Filming them is too time-consuming. Better to leave the car company's ads to pros like Ricardo Montalban and John Houseman (who also have done Chrysler commercials), he says.

''I wish I could have my privacy back,'' Mr. Iacocca lamented to an interviewer recently. Chrysler spokesmen seem to echo their chief executive's dissatisfaction with doing commercials by insisting there are no plans for him to do more.

Victor Kiam, who heads Remington Products Inc. of Bridgeport, Conn., is another chief operating officer who has parlayed his forceful and driving personality into almost instant TV fame - and Remington fortune.

His commercial, perhaps the ultimate product testimonial, describes how he came to head the company: ''I was a dedicated blade shaver until my wife bought me a Remington microscreen shaver. . . . I was so impressed, I bought the company. Remington microscreen shaves as close as a blade, or I'll give you your money back.''

Since the commercials were aired four years ago, company profits have climbed dramatically, and the Remington work force has gone from 750 to more than 1,000 people. CEO Kiam has one slight regret, however. He used to like to grow a beard in the winter. Now, he doesn't dare go out of the house unshaven, a company spokesman says.

Some advertising industry analysts say it's unlikely that Iacocca, Perdue, and Frank Borman, CEO of Eastern Airlines, will stop appearing in commercials.

The analysts give several reasons. There is a conviction that buyers are better influenced by ''the man in charge.''

''There's a certain believability about them you don't get from trained actors,'' says a spokesman for the American Association of Advertising Agencies in New York.

''The casting of a commercial can make or break an ad campaign or an agency, '' says Wilder Baker, president and chief operating officer of Warwick Advertising Inc. ''A prime point is that a speaker (in a commercial) has to be in keeping with the character of the product.''

This credibility comes in handy, insiders say, when a company wants to to dramatically improve its public image, as has been the case with Chrysler.

One industry expert - who asked not to be named - says in some cases, vanity plays a role. One firm's commercials bombed so badly that sales dropped, he says. But the firm's chief executive continues to appear before the cameras despite the protests of his ad agency. He then fired the agency.

According to the mail that pours in to companies with CEOs doing commercials, a great many people take notice of the ads - even when the ads are heard on radio. Former New York Gov. Malcolm Wilson, chairman of the board of Manhattan Savings Bank, only makes radio commercials. But he says many people, including former New York Gov. Hugh Carey, have told him how much they enjoy his ''commercials on TV!''

The danger in this - as for all commercials - is that viewers' attention may become more focused on the ads than on the products. Madison Avenue's history books are filled with ''red ink'' examples of commercials that were better at selling themselves than the goods they represented.