Sidney Gottlieb, who presided over the Central Intelligence Agency's cold-war efforts to control the human mind and provided the agency poisons to kill Fidel Castro, died on Sunday in Washington, Va. He was 80 and had spent his later years caring for dying patients, trying to run a commune, folk dancing, consciousness-raising and fighting lawsuits from survivors of his secret tests.

Friends and enemies alike say Mr. Gottlieb was a kind of genius, striving to explore the frontiers of the human mind for his country, while searching for religious and spiritual meaning in his life. But he will always be remembered as the Government chemist who dosed Americans with psychedelics in the name of national security, the man who brought LSD to the C.I.A.

In the 1950's and early 1960's, the agency gave mind-altering drugs to hundreds of unsuspecting Americans in an effort to explore the possibilities of controlling human consciousness. Many of the human guinea pigs were mental patients, prisoners, drug addicts and prostitutes -- ''people who could not fight back,'' as one agency officer put it. In one case, a mental patient in Kentucky was dosed with LSD continuously for 174 days.

Other experiments involved agency employees, military officers and college students, who had varying degrees of knowledge about the tests. In all, the agency conducted 149 separate mind-control experiments, and as many as 25 involved unwitting subjects. First-hand testimony, fragmentary Government documents and court records show that at least one participant died, others went mad, and still others suffered psychological damage after participating in the project, known as MK Ultra. The experiments were useless, Mr. Gottlieb concluded in 1972, shortly before he retired.