Hostility can kill -- not just the victim, but the aggressor as well. New medical research links this angry attitude with a host of physical ills, from headaches to cancer.

Hostile people have five times as many heart attacks and a five-fold higher death rate from all causes than those who are slow to anger, according to recent studies by Duke University psychiatrist Redford Williams Jr. "The higher the hostility score, the more likely that person will have significant blockage of the arteries--the major underlying lesion in heart attack victims."

Hostility is one trait of "Type A" people--a personality also characterized by impatience, high ambition and the tendency to do several things at once. "We know that Type A's have more heart attacks," says Williams, who estimates "at least half the population" is Type A. "We wanted to uncover what traits might be responsible."

Among his findings:

In a long-term study of 255 medical students, 10 percent of the high-hostility scorers had developed coronary artery disease 25 years later. Only 2 percent of the low-hostility scorers had developed the disease. Less than 3 percent of the low-hostility group had died, while 14 percent of the high hostility group were dead.

In a study of 424 men and women, 46 percent of the high-hostility, Type A women had significant arterial blockages, while just 12 percent of the low-hostility, Type B women did. About 85 percent of the high-hostility, Type A men had significant blockage, while 55 percent of the low-hostility, Type B men did.

High-hostility women have a greater relative risk of disease or death than high-hostility men, since "women have a much lower morbidity and mortality rate overall than men."

Why is hostility harmful to health? One theory, says Dr. Williams, is that chemicals released into the body during anger literally wear down the system.

Another possible explanation: "People who have hostile attitudes are going to be a lot less likely to have social support . . . and having people you can depend on is important to your health."