"Andrew Wyeth: The Helga Pictures," an exihibition of 107 drawings and watercolors by the popular and controversial American artist, opens tomorrow at the Museum of Fine Arts.

Executed during a 15-year span from 1971 to 1985, the suite of drawings focuses exclusively on a single model, Wyeth's neighbor Helga Testorf of Chadds Ford, Pennsylvania.

The paintings created a stir last summer when Wyeth revealed that he had been working with the model in secret for 15 years. He sold the works for $10 million and received national media attention unusual for an American artist.

"Such close attention by a painter to one model over so long a period is a remarkable, if not singular, circumstance in the history of American art," writes John Wilmerding, deputy director of the National Gallery of Art in Washington, D.C. and author of "Andrew Wyeth: The Helga Pictures."

The exhibition, which will remain in Boston through January 3, 1988, can only be viewed by reserving a ticket through TICKETRON or the museum's Wyeth box office. Tickets are $6, $4 for senior citizens and children ages 6-16. Museum hours are Tuesday-Sunday, 10 a.m.-5 p.m. and Wednesday, 10 a.m.-10 p.m.

The Helga Pictures consist of groups of 30 different interrelated poses. Helga is shown nude and clothed, posed against doors and windows, and asleep and awake during different seasons and times of day. The effect, according to museum publicists, is to convey a sense of morality and the passing of time.