Since biblical times, when lepers were advised to bathe their afflicted skin, Israel's healing waters have drawn visitors.

Today, vacationers in Israel seeking relaxation, beauty treatment or cures for their ailments still flock to Israel's many hot springs and the spas clustered nearby.

Northern Israel's Tiberias Hot Springs Health Center is a vast, spring-studded complex treating rheumatoid arthritis, lumbago, sciatica and muscular diseases. Naturally occurring sodium chlorate and calcium compounds render the water hypothermic and hypertonic, while the restorative powers of piloma, a therapeutic mudlike mineral sediment, are also touted.

Visitors often buy packages of mud to take home for future use.

Enormous indoor and outdoor pools overlook the Sea of Galilee. Ultrasound and physiotherapy are available, along with medical supervision and solarium treatment for psoriasis. Paralyzed individuals can get special attention from professionals, many of whom learned their skills while working with war victims.

Across the street are the ruins of an ancient spa.

Visitors can opt to stay at the Galei Kinneret Hotel, the Tiberias area's top-rated hostelry, which has 107 rooms and a gourmet restaurant. Numerous celebrities including Danny Kaye, David Ben-Gurion, Marc Chagall and Pierre Mendes-France have enjoyed its charms. There are about three dozen other hotels and hostels to choose from.

About 13 miles away at Hamat Gader are vast, complex Roman baths that were used from the second to ninth centuries and which are now held among the world's most impressive ruins. Archaeolo-gists excavating in 1979 found 5,000 ancient coins and thousands of glass bottles and pottery shards scattered about the red, white and green marble floors and frescoed walls. Corinthian columns and arches grace the complex's 1 1/3 acres.

Most visitors today come to Hamat Gader seeking help with bone and muscle problems. The gigantic 140-foot-long outdoor pool is fed by a natural spring, and water returns from the pool to the Yarmuk River.

The spa's kibbutz, which includes massage facilities and bathhouse, can accommodate 7,000 guests at one time.

At Israel's southern end, numerous spas flank the Dead Sea. Here, the availability of mineral-laden hot springs and therapeutic mud are aided by the climate, where high atmospheric pressure 1,300 feet below sea level results in a 10 percent higher level of oxygen than at sea level — the world's highest. There's also a higher concentration of long-wave or UVA light than in other parts of the world. Cancer-causing UVB rays are naturally filtered out, so sunbathers can lie exposed for long periods without worry.

Every year some 10,000 psoriasis sufferers flock here to float in the buoyant, salty waters. Physicians at Ben-Gurion University found that psoriasis disappeared or showed significant improvement in 85 percent of visiting suffers.

For heavy-duty skin treatment, visitors choose the spa run by the Kibbutz Ein Gedi, which accommodates visitors in its rustic guesthouses. Thousands every year arrive at this immaculate facility for help with rheumatoid, respiratory and dermatological ailments. Many maintain memberships. The six indoor pools offer treatment at prices more affordable than at nearby hotels.

Some guests prefer staying at the more luxurious hotels a 40-minute drive away in Jerusalem, including the outstanding Laromme Hotel or the old-world King David, returning daily for treatment.

Another option is the Hyatt Regency Jerusalem, which boasts its own spa. This 3,000-square-foot state-of-the-art facility features fitness equipment as well as health and beauty programs.

Israel offers a variety of accommodations for those who crave its healing waters. The Israel Government Tourist Office (350 Fifth Ave., New York, NY 10118; (212) 560-0650) can supply lists of accommodations and treatments, plus professional analyses of various springs and facilities.

Two tour operators, Isram Travel, (800) 223-7469, and Jericho Spa Tours, (800) 538-8383, proffer specialized psoriasis-treatment packages.

El Al Israel Airlines flies daily nonstop flights (except on the Sabbath and holidays) from New York, with several flights weekly from the gateway cities of Chicago, Miami, Boston, Baltimore-Washington, Dallas-Ft. Worth and Los Angeles. For schedule and airfares, call (800) EL AL SUN.