Amanda Knox, 26, and Raffaele Sollecito were found guilty in 2009, but acquitted on appeal in 2011.
In March, Italy’s highest court overturned both acquittals, ordering a fresh appeals process.
Amanda Knox spent four years in prison before her acquittal. She has always insisted that she is innocent.
The retrial is due to open in the central Italian city of Florence, and the first session is expected to discuss procedural issues such as dates for further hearings.
The retrial was ordered after the prosecution had taken the case to Italy’s Supreme Court.
The court strongly criticized the way the appeals court had dismissed important DNA evidence, ordering the whole process to begin all over again.
Amanda Knox is not required to be present for the retrial.
Earlier this month, she said she expected to win another acquittal, but that “common sense” told her not to return to Italy.
“I was already imprisoned as an innocent person in Italy,” she told America’s NBC television.
“I just can’t relive that.”
“I thought about what it would be like to live my entire life in prison and to lose everything, to lose what I’ve been able to come back to and rebuild.
“I think about it all the time. It’s so scary. Everything is at stake.”
However, if her previous conviction is confirmed, Italy would be expected to request her extradition.
Meredith Kercher, from Coulsdon, south London, was found dead in a flat she shared in Perugia with Amanda Knox, a fellow exchange student.
Both Amanda Knox and Raffaele Sollecito maintain their innocence.
Raffaele Sollecito is expected to attend some of the hearings, reports in local media say.
Amanda Knox insists that on the night of Meredith Kercher’s death she was at Raffaele Sollecito’s flat, smoking marijuana and watching a film.
Another man – Rudy Guede from Ivory Coast – was convicted in a separate trial and sentenced to 16 years for the killing.
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