Kenyan cult leader Paul Mackenzie and 29 associates were charged with the murder of 191 children, whose bodies were discovered buried in a forest.
The accused denied the charges in a court in Malindi. One defendant was deemed mentally unfit for trial.
Prosecutors allege Mackenzie instructed followers to starve themselves and their children to attain heaven before the world's end, marking one of the worst cult-related tragedies in recent history.
Members of Mackenzie's Good News International Church resided in secluded settlements spanning 800 acres within Shakahola forest, where over 400 bodies were unearthed.
Mackenzie was arrested April last year and has already been charged with terrorism-related crimes, manslaughter and torture. He was also convicted in December of producing and distributing films without a licence and sentenced to 12 months in jail.
A former taxi driver, Mackenzie forbade cult members from sending their children to school and from going to the hospital when they were ill, branding such institutions as Satanic, some of his followers said.
Mackenzie's lawyer has said he is cooperating with the investigation into the deaths. The 30 defendants are due back in court on March 7 for a bond hearing, the judge said.