NEW YORK - George B. Rathmann, who was the first chief executive of Amgen and helped build it into the world’s largest biotechnology company, died Sunday at his home in Palo Alto, Calif. He was 84.

In confirming the death, his son James said Mr. Rathmann had suffered from kidney failure for several years.

Mr. Rathmann is widely considered one of the fathers of the biotechnology industry. There was only a handful of companies involved in genetic engineering in 1980, when Mr. Rathmann was recruited from Abbott Laboratories to run Amgen, which was little more than a vague idea by some venture capitalists to start a company, without knowing exactly what the company would pursue.

But during the next eight years, Mr. Rathmann focused Amgen on developing what would become two of the most successful drugs in history: Epogen, to treat anemia, and Neupogen, which helps cancer patients receiving chemotherapy avoid infections.

“He was the one who created the company, without any doubt,’’ said Lowell Sears, a former chief financial officer at Amgen, based in Thousand Oaks, Calif. In 1990, after stepping down as chief executive at Amgen, Mr. Rathmann cofounded Icos, which developed the erectile dysfunction drug Cialis and was acquired by Eli Lilly & Co.

Mr. Rathmann came to biotechnology relatively late in his career.

He started out working about 20 years at 3M, working on Scotchgard and other products, before becoming head of research and development for the diagnostics division of Abbott Laboratories in 1975. (He also worked briefly for Litton Medical Systems.)

In the late 1970s, after scientists learned how to splice genes from one organism into another, Mr. Rathmann decided, as he later told an interviewer, that “this was the most important thing I had ever seen.’’ He persuaded Abbott to give him a leave of absence to work in a lab at the University of California, Los Angeles, to learn the technology.