Pope John Paul II on Thursday night underwent tracheotomy in Rome's Gemelli Hospital to ease his breathing.
The operation took place hours after he was admitted to the hospital with a recurrence of the flu.
The operation, which involves making a hole in the throat through which a tube is inserted to assist breathing, took about 30 minutes and ended at 0850 pm, according to reports.
"He's fine, and he's tranquil," said Gianna Letta, under-secretary for Italian Prime Minister Silvio Berlusconi. "The doctors are satisfied with the way he has undergone the surgery."
The 84-year-old pontiff spent 10 days in Gemelli Hospital earlier this month suffering flu symptoms.
