Deep in the heart of Italy's Valle d'Aosta, at the far end of the valley of Valgrisanche, is one of Europe's only permanent helicopter ski bases, set in a paradise of virgin powder.

Valgrisanche -- a small, isolated valley south of Mont Blanc -- is surrounded by some of the Alps' most spectacular peaks. For centuries it was a small but prosperous mountain community known for the quality of the cloth that it wove. Then came the great plague, and the inhabitants either died or fled in terror.

Decades later a few shepherds and some landless peasants filtered back into the valley, and the years that followed saw little growth. Even in this century, the developers and tourists have not descended. The valley was too far away from either St. Bernard's Pass, the great north-south axis across the Alps, or the newer Mont Blanc Tunnel to attract more than an occasional dedicated mountain climber.

But in 1982 Jean-Marc Durieux, a former Swiss ski racer and equipment designer (he built the first "brake" to stop runaway skis) came across Valgrisanche while working as a mountain guide at Chamonix, a French ski resort not far away.

A year later he created a company called Heliski Lacadur, and with a chartered helicopter started landing dedicated skiers on the unspoiled peaks surrounding the valley. Last season, Durieux brought more than 1,000 skiers to the pristine slopes of Valgrisanche between January and May. Today Heliski Lacadur is a well-established operation -- and a well-kept secret.

The home base of Heliski Lacadur is the Hotel Perret, a solid stone and wooden structure, built 20 years ago by the uncle of the present owner. Here the ambiance is definitely alpine, with the rough edge of authenticity. The hotel can house only 25 guests. The rooms, though impeccably clean, are small. Each has minimal furniture and a wash basin with hot and cold water. Toilet and shower rooms are down the corridor. Meals are taken at the communal table. Food, cooked by the owner's wife, is tasty and plentiful, and the wine -- the only item not included in the price -- is strong and full bodied.

Next door, one of the local guides has opened a second hotel, La Maison des Myrtilles (The House of Blackberries -- the valley is partly French-speaking), which can house 20 guests in 10 double rooms, each with a private shower.

Durieux does not accept more than 35 skiers at a time, divided into five groups of seven plus one guide. On average, however, there are rarely more than two groups at a time.

Guests check in before dinner. After dinner, Durieux briefs them on what is planned for the following day. He has a radio link to the control towers of the Geneva and Milan airports to check on the coming weather. (Valgrisanche, being on the south side of the Alps, enjoys relatively favorable conditions. Between the end of January and the end of March 1984, there were only 10 days when the helicopter could not fly.)

Skiers also receive a small radio beacon to carry in case they are caught in an avalanche. A receiver in the helicopter can locate the beacon at a distance of 1,800 feet under 18 feet of snow. Each guide has a two-way radio and is in constant contact with the helicopter and the Hotel Perret.

In midwinter the day starts around 9 a.m., when the silence of the valley is broken by the sudden whine of the helicopter's engine warming up. Parked next to the Hotel Perret, the helicopter is a French-built Lana, the flying workhorse of the Alps. The pilot and a mechanic live at the hotel.

The helicopter starts off with three skiers and the guide. It then flies back to the hotel -- a matter of a few minutes -- to pick up four more skiers. When the seven skiers and the guide have linked up, the descent starts. Meanwhile -- in an incessant ballet -- the helicopter is ferrying other groups.

Skiers generally are landed at 10,000 feet on any of seven major peaks, and they ski down to an altitude of about 4,500 feet. On arrival, they find the helicopter waiting to transport them to another peak. Most of the skiing is done on glaciers, but these -- in alpine jargon -- are not "open" and so there are practically no crevices.

Depending on the weather, skiers in the winter generally do two runs in the morning, go back to the hotel for lunch and do one run in the afternoon, totaling about 15,000 vertical feet of skiing a day. In the spring, the day starts earlier and ends around 2 p.m. with lunch at a mountain refuge, or sometimes a picnic is brought by helicopter before the last run home.

Snow conditions vary, of course, but winter brings the lightest powder. Waiting in line or skiing the same run twice are unheard of here.

Skiers at Valgrisanche are a diverse group. My group included a Genevese banker with his wife, a heavily titled Spaniard, an Austrian socialite, an American female executive from Paris and a local inhabitant from the valley. All valued the exclusivity of Valgrisanche. Most skiers stay for three days, with some coming every year for one full week.

Valgrisanche is not for beginners, but stamina takes precedence over style -- provided one can turn in powder snow. It's an experience not to be missed.