Lantos, a native of Hungary who survived the Holocaust, was serving his 14th term in Congress when he announced Jan. 2 that he would not seek re-election after being diagnosed with cancer.
His congressional office announced Monday that Lantos had died.
He was chairman of the U.S. House of Representatives Committee on Foreign Affairs and was also a senior member of the House Committee on Oversight and Government Reform.
"It is only in the United States that a penniless survivor of the Holocaust and a fighter in the anti-Nazi underground could have received an education, raised a family, and had the privilege of serving the lasts three decades of his life as a member of Congress," Lantos said in announcing his decision to step down.
Lantos is survived by his wife of nearly 58 years, Annette; two daughters; 18 grandchildren; and two great-grandchildren.
His Web site says the date for a public memorial service hasn't been set.