For 150 years, Swazi men such as Howard Mlondolozi Dlamini honored the wishes of a long-dead king who, fearing for the readiness of his young troops, banned the time-consuming rituals of circumcision that mark the arrival of adulthood throughout much of Africa.

Today, the biggest threat to Swaziland is not invasion but AIDS, and a study in neighboring South Africa has revealed male circumcision decreases the likelihood of contracting the disease. As news spreads, the surgery has made a sudden comeback in a country that has among the world's lowest rates of circumcision and the highest rates of HIV infection.

In recent months, hundreds of Swazi men have been circumcised. Dlamini, 42, a traditionalist who often wears a red patterned Swazi cloth knotted at the shoulder rather than Western clothes, underwent a 30-minute procedure in September.

``I have seen people dying left and right, and leaving children,'' said the hospital! administrator and father of two, who has lost three close relatives to AIDS. Speaking in the nearby city of Manzini, he recalled thinking, ``To take good care of my children, let me undergo the procedure.''

Even now, with lifesaving retroviral drugs increasingly available, the AIDS rate in Swaziland remains extremely high. The United Nations estimates that two of every five working-age adults are infected with HIV. About 20,000 people here last year died of complications caused by AIDS, and in the past decade the disease has lowered life expectancy from 57 years to 33. There is worry AIDS could severely depopulate Swaziland, a tiny nation of 1.2 million people on the border between South Africa and Mozambique. ``I worry that this younger generation will be wiped away,'' Dlamini said.

SHIFT IN ATTITUDES

As hospital wards overflow, avoiding HIV has become a consuming concern for Swazis. Since the South African report appeared saying that circumc! ised men are 60 percent less likely to contract HIV, the shift in Swaz i attitudes toward circumcision - once widely viewed as unmanly - has been dramatic and swift.

Hospitals that once rarely performed circumcisions have recently been doing 10 to 15 a week, with two-month waiting lists. A physician with a radio show has called on his listeners to have the surgery, which removes the foreskin and along with it the cells most vulnerable to HIV. A lawmaker has advocated the procedure in a speech to parliament and demanded that the government increase capacity and subsidies for it.

Although some international donors have warned the study is not definitive, and some critics in the United States and elsewhere regard male circumcision as a form of mutilation, many Swazi men, and in some cases women, are taking action.

After learning of the research, Lungile Maziya, 35, a pharmacy technician, scheduled circumcisions for all four of her sons, aged 6 to 15. She also scheduled the surgery for her husband, a practical precaution in a nation where polygamy is still practiced and wives in monogamous marriages rarely count on faithfulness from their spouses.

Only her 15-year-old balked. She said she told him, ``My boy, when you're 18, you'll really thank me for this.''

Ritual circumcision once was routinely practiced across sub-Saharan Africa as boys reached puberty. But it has become far less common, especially in southern Africa, as traditional values slipped away and young Africans have moved to densely packed urban areas.

DRAWBACKS

The study has been attacked by opponents of circumcision in the United States and Europe, who regard it as akin to female genital mutilation.

There are other drawbacks. In the first several weeks after the surgery, men are actually more vulnerable to HIV because the virus can easily enter the wound. Even some advocates of circumcision worry newly circumcised men may wrongly believe they are totally protected and engage! in more high-risk sexual behavior.

The South African study, in fact, found an increase in the number of sexual partners among the circumcised men, though even with their riskier behavior, they still contracted HIV far less frequently than those who were not circumcised.

Marwick T. Khumalo, a legislator who credits circumcision with protecting him from HIV, has put his advocacy in explicitly Swazi terms, telling parents their paternal bloodline depends on protecting their sons from the virus.