Since Mass. General and Harvard appointments go hand in hand and McCully had not been recommended for tenure at Harvard, both jobs formally ended in January 1979. At about the same time, a former classmate at Harvard who went on to become the director of the Arteriosclerosis Center at M.I.T. attacked his ideas as ''errant nonsense'' and a ''hoax that is being perpetrated on the public.'' McCully says that when he was interviewed on Canadian television after he left Harvard, he received a call from the public-affairs director of Mass. General. ''He told me to shut up,'' McCully recalls. ''He said he didn't want the names of Harvard and Mass. General associated with my theories.''

In retrospect, it seems clear that McCully was a man ahead of his time when the times were all about cholesterol. ''Kilmer McCully's hypothesis seemed to challenge the cholesterol-heart hypothesis, which was riding high,'' says Irwin Rosenberg, director of the U.S.D.A. Human Nutrition Research Center on Aging at Tufts University. Rosenberg was a medical-school classmate of McCully's and, briefly, a physician in Mass. General's department of medicine when McCully was in the department of pathology. ''Because his work was not in vogue,'' Rosenberg says, ''his insistence on what he was doing contributed to costing him his job.''

Thomas N. James, a cardiologist and president of the University of Texas Medical Branch who was also the president of the American Heart Association in 1979 and '80, is even harsher. ''It was worse than that you couldn't get ideas funded that went in other directions than cholesterol,'' he says. ''You were intentionally discouraged from pursuing alternative questions. I've never dealt with a subject in my life that elicited such an immediate hostile response.''

It took two years for McCully to find a new research job. His children were reaching college age; he and his wife refinanced their house and borrowed from her parents. McCully says that his job search developed a pattern: he would hear of an opening, go for interviews and then the process would grind to a stop. Finally, he heard rumors of what he calls ''poison phone calls'' from Harvard. ''It smelled to high heaven,'' he says. ''Eventually I went to an attorney friend of mine, someone quite prominent in Boston. He made a few phone calls and it was all over. Then this job came through.''

The story of those two scary, free-fall years -- McCully can still recite the exact dates, Jan. 1, 1979, to March 15, 1981 -- emerges in small details, teased out by questioning. This is not a man who eagerly lays his grievances on the table. ''My daughter told me recently that she still gets nightmares about that time,'' he says. Later, describing his son's and daughter's careers as, respectively, Wall Street banker and magazine editor, he remarks: ''They both had been interested in chemistry when they were younger. Then they saw what happened to me'' -- he barks a laugh -- ''and that was the last I ever heard about that.''

McCully also laughs with seeming good grace about the contrast between his present position and that of medical-school classmates like Irwin Rosenberg, ''the director of the nutrition institute at Tufts, with a multimillion-dollar budget and all these projects.'' But from his much more modest perch at the Providence V.A. lab, he says, ''I've been able to develop my own approach, which might not have been possible at a high-powered place.''

When McCully landed in Providence, he continued testing his theories, inducing arteriosclerosis in rabbits, observing homocysteine's effect on cancer cells and publishing his first monograph, an overview of the homocysteine theory. At the same time, a study at Cornell and several others in Europe -- in Sweden, Norway, the Netherlands and Ireland -- explored the workings of homocysteine in humans. By 1990, some of those results were beginning to pique fresh interest in the United States, and Meir Stampfer, a professor of epidemiology and nutrition at the Harvard School of Public Health, decided to take a look at homocysteine in members of the Physicians Health Study, an ongoing survey of almost 15,000 doctors. Stampfer's findings helped start the current surge in homocysteine research.