Cardinal Karl Lehmann, 71, announced Tuesday his resignation as chairman of the German Conference of Catholic Bishops on health grounds, but said he would continue as bishop of his own diocese, Mainz.
Lehmann, an internationally known theology scholar, has been the voice of German Catholicism for two decades.
He said Tuesday he had concluded he was overworking after he was admitted to hospital at the end of last year with heart palpitations.
"The demands from public life and the media, the personal meetings and the letter writing keep on increasing. Recently I was overdoing it," he said in a letter to the heads of the other 26 dioceses.
A theological moderate, Lehmann cultivated close relations with German Protestants and Jewish groups and several times clashed with his more conservative counterpart, Joseph Ratzinger, now Pope Benedict XVI, over church government.
The two men share the same background of highly academic German seminary training, emerging as young radicals in Rome at the Catholic Church's Second Vatican Council 1963-1965 and being promoted to bishop and cardinal.
The German church is a key financial backer of the Vatican, thanks to an income tax on its 26 million members, though faith has suffered a decline with only 14 per cent at mass on any one Sunday and only 264 men volunteering last year to become priests.
Lehmann said his resignation, effective February 18, would enable a change of generation in the bishops' conference, with top posts recently taken over by men younger than or just past 50.
The 71 archbishops, plain bishops and auxiliary bishops are to meet February 11-14 to elect a replacement.
The premature retirement cuts short his fourth term of six years which began in September 2005.
Lehmann, a solid man with a booming laugh, became bishop of Mainz in 1983, chairman of the conference in 1987 and was elevated to cardinal in 2001. Silver jubilee celebrations are planned in Mainz Diocese this October to mark his long leadership.
Charlotte Knobloch, president of Germany's Council of Jews, said Tuesday Lehmann was not only a man she and her predecessors could trust, but that Jews would miss him as a friend. ( Dpa )