Judge Chaudhry Habib-ur-Rehman would be on leave till October 26 due to his health problem, special public prosecutor Chaudhry Zulfiqar Ali told PTI.
The trial has been adjourned till next month as the judge's leave would be followed by the Eid holidays.
The exact nature of the judge's health problem could not immediately be ascertained.
Lakhvi and six other suspects have been charged with planning, financing and facilitating the 26/11 attacks that killed 166 people in Mumbai.
The judge of the Rawalpindi-based anti-terrorism court has been conducting the trial behind close door at Adiala Jail for security reasons.
Ali said the Federal Investigation Agency would also pursue two petitions in the Islamabad high court to get Ajmal Kasab, the lone surviving attacker, declared as proclaimed offender or fugitive and to obtain voice samples of the seven suspects.
These measures were necessary to take forward the prosecution of the seven suspects, he said.
Image: A burning Taj Mahal Palace Hotel during the 26/11 terror attacks in Mumbai