For more than 500 years, Italians have been discovering and rediscovering America. The latest landing is by three fashion companies eager to expand their global success to these shores. Marzotto, Maska and Max Mara have all been available in the United States in limited distribution but are now gearing up for major expansion.

There are two main reasons for the timing, said Sergio Garretti, the president of the Marzotto (U.S.A.) Corp."The devaluation of the lire gave us an economic reason," he said. "The crisis of traditional European markets caused a major push to find new places for our product. And we are aware of the need to adapt our product to American needs."

Marzotto, a 158-year-old company with annual sales of $1.2 billion, distributes seven men's and three women's wear lines in the United States. The women's lines are Missoni Donna, Studio 000.1 by Gianfranco Ferre and its own Accento.

The current emphasis is on adapting the styling and merchandising of Accento and the fit of the clothing and the delivery schedule of Studio 000.1 so both lines can be offered to a wider range of stores here.

Maska has been in business since 1967 with a succession of uncredited designers, including Ferre, Walter Albini, Jean-Paul Gaultier and Franco Moschino.

The collection has been available in the United States sporadically since 1989, but Adriano Luca Davoli, the vice president and general manager of Maska's United States division, intends to change that. The spring collection is now being shown to major stores in a new showroom in New York at 650 Fifth Avenue - the preferred address of many European fashion houses - by Travis Winberg, who brought Genny and Byblos to this country a decade ago.

Max Mara, with annual sales of $1 billion, is introducing a new advertising campaign in fashion magazines in September, the same month it is to open its first New York boutique at 813 Madison Avenue (68th Street). There are also plans for 15 more boutiques across the country in the near future.

Aside from their country of origin, the three companies have other common denominators. Styling is more traditional than high fashion and prices seldom top $1,000 for an outfit.