Pope John Paul II's health has deteriorated further, the Vatican said.
His breathing is shallow, his blood pressure is low and he is having difficulties with both his heart and kidneys, a spokesman said.
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Millions around the world have been praying for the Pope, and a special Mass was held in Rome on Friday.
During a rosary service in the square Friday night, Monsignor Angelo Comastri, the vicar of Vatican City, said that soon "Christ will open the doors to the pope."
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In Krakow, Poland, where John Paul served as archbishop before becoming Pope, thousands of people gathered at the archbishop's residence, many carrying candles and crying, CNN reported.
The crowd prayed and sang for their fellow Pole.