Marlin Perkins, 81, a zoologist, explorer and zoo keeper who brought nature into the nation's living rooms for years as host of "Wild Kingdom," one of television's most popular and longest-running shows, died yesterday at his home in St. Louis. He had suffered from lymph cancer for two years.

A former director of zoos in Buffalo, Chicago and St. Louis, Mr. Perkins was also a television pioneer who began presenting animals on the air in 1945.

Illness forced him to leave "Wild Kingdom" last year after 23 seasons in which he led millions of viewers to animal habitats all over the world.

At the height of its popularity, "Wild Kingdom," which was an NBC network show for nine years and was later syndicated by its original sponsor, the Mutual of Omaha insurance company, was seen on 200 stations in North America.

It won four Emmy Awards.

Mr. Perkins was born in Carthage, Mo., on March 28, 1905. Boyhood days on a farm, spent watching the insects, mice and other creatures unearthed in plowing, helped arouse his interest in animals. As a third grader, living with an aunt, he collected snakes and kept them in boxes under her house. When she found out, he recalled, "she raised the roof."

In 1926, Mr. Perkins, a college dropout, joined the St. Louis Zoo as a laborer. By 1928 he was reptile curator. In 1938 he left St. Louis for other zoo posts but returned in 1962 as director.

He became known for innovation, developing zoo nurseries, improving nutritional programs, placing vivid labels on exhibits, showing animals in their natural habitats and setting up breeding preserves. He was particularly concerned about protecting endangered species.

In pretelevision days in St. Louis, he showed an interest in radio. Electric eels he used in a demonstration once knocked a local station off the air.

In Chicago, there were only about 300 television sets in the city when his show, "A Visit to the Lincoln Park Zoo," made its 1945 debut.

In 1949 came Mr. Perkins' "Zoo Parade." It was an instant hit and lasted eight years.

"There's lots of room for animal shows," he said in an interview years later. "But we were the first one, and that went on the air the minute the cable went into service between Chicago and New York."

In its last years "Zoo Parade" began the location shooting that later became the hallmark of "Wild Kingdom." Its viewers became accustomed to seeing Mr. Perkins in what sometimes appeared to be hazardously close encounters with wild creatures in their native swamp, jungle or river.

Part of the secret of Mr. Perkins' success was his unabashed and undisguised love for animals, including those of dubious reputation, such as snakes and wolves.

"I've never seen an ugly animal in my life," he once said. "To me, they're all beautiful."

Nevertheless, Mr. Perkins received his share of injuries. A Gaboon viper's bite almost killed him in St. Louis in 1928. An elephant broke three of his ribs once during filming in India.

Survivors include his wife, Carol; a daughter, Suzanne Perkins of Berkeley, Calif.; two stepdaughters, Alice Goltra of Lake Forest, Ill., and Marguerite Sorum of Washington, and a stepson, Fred Cotsworth of St. Louis.