The film producer, whose credits include Pretty Woman, Free Willy and The Client, is said to be too ill to travel to Israel for the trial.
Prosecutors allege that in exchange for gifts Netanyahu asked US officials to extend Milchan's resident's permit in the country and extended regulations exempting Israelis returning from abroad from declaring foreign income.
Netanyahu, who is charged with fraud and breach of trust, has denied all allegations of wrongdoing, saying he was not acting in Milchan's personal interests and even occasionally acted against them. The exchanges of gifts were simply friendly gestures, he has said.
The prime minister was seen on Wednesday accompanying his wife Sara at Ben Gurion Airport, as she prepared to fly to London to be present for Milchan’s testimony.
His defence attorney has said Netanyahu wanted to exercise his right to be present but could not clear the time to travel so asked his wife to attend in his place.
Demonstrators are arranging to meet outside the courthouse, bringing with them Israeli flags and drums.
