By LARRY ROHTER

Published: Saturday, August 3, 2002

Msgr. James M. Ryan, a Roman Catholic missionary from Chicago who was one of the central figures of religious and civic life in the Amazon for more than half a century, died in Chicago on July 12. He was 89 and had lived in Santarém, Brazil, since 1943.

The cause of death was cancer, according to church leaders.

As the bishop of Santarém for more than 25 years, Bishop Ryan administered the largest diocese in the world, a harsh jungle domain that, at more than 125,000 square miles, was larger than many European countries. Known popularly throughout the Amazon as Dom Tiago, he oversaw the building of clinics, schools, churches and a radio station in a part of Brazil that was often neglected by the central government 2,000 miles away.

''In 60 years as a pioneer, he acted with passion and made those who heard his voice and witnessed his commitment also feel a passion for the region,'' recalled Lucio Flávio Pinto, a native of Santarém who is editor of Amazon Agenda, the leading newsletter in the area. ''In that missionary effort, he gave the maximum of himself and respected positions that diverged from his.''

James Ryan was born in an Irish neighborhood on the South Side of Chicago on Nov. 17, 1912. He was ordained a priest in 1938 and initially taught English, speech and drama at a Roman Catholic seminary in Illinois.

But in 1943, he and three other Franciscan friars from the Middle West volunteered to go to Brazil. ''We had no idea where Santarém was,'' he said in an interview last year, ''but it was wartime, we wanted to do something, and it all seemed like a grand adventure.''

At first, he was assigned to Fordlandia, a plantation operated by the Ford Motor Company on the banks of the Tapajós River to supply rubber to the war effort. When the rubber project closed down at the end of World War II, he was asked to stay on by ecclesiastical authorities, who were chronically short of priests willing to minister in the Amazon's exhausting environment.

For more than a decade afterward, he preached and provided the sacraments to Catholics at dozens of remote chapels and churches scattered around the region, often traveling by small motorboat or even canoe. Unusually tall, at 6 foot 4, and with a strong American accent to his Portuguese that he never lost, he became one of the familiar and admired notables in the Amazon.

In 1958, he was made bishop of Santarém. A military dictatorship took power in Brazil in 1964, and in the years that followed, Bishop Ryan, a theological conservative whose views were softened by Vatican II, became known as a staunch defender of human rights and the environment, using the diocese radio station to denounce abuses and corruption even when local army commanders threatened to have him expelled.

After retirement in 1985, Bishop Ryan tried briefly, on the advice of his doctors, to live in a retirement home in Chicago. But the pull of the Amazon proved too strong, and he returned and moved into a small house overlooking the Tapajós River where he could read, write and receive the steady stream of visitors who continued to come his way, ranging from peasants to politicians.

Life in the United States ''just wasn't like here,'' he said last year. ''This is home.''

Bishop Ryan is survived by three brothers, John, Vincent and Elmer, and more than a dozen nieces and nephews. He was buried in the Cathedral of Nossa Senhora da Conceiçao in Santarém, just a block from the Amazon River.

Photo: Bishop James M. Ryan getting a hug from a parishioner last October in Santarém, Brazil, where he chose to live after he retired in 1985. (Larry Rohter/The New York Times)