The 61-year-old, of Dublin Road, Dromore, Co Down, is accused of 18 offences, which allegedly occurred between 1985 and 2008.
The case facing the former Lagan Valley MP involves two female complainants.
The charges include one of rape, four counts of gross indecency and 13 counts of indecent assault.
His wife, Lady Donaldson, 58, of the same address, also pleaded not guilty at the arraignment hearing, to three charges related to aiding and abetting indecent assault on a female.
She has also been charged with aiding and abetting rape and child neglect.
Her lawyers have applied to have these two charges against her withdrawn.
The couple were arrested at their home in March 2024 and are on continuing bail.
Judge Paul Ramsey KC set the trial date for March 24, 2025.
The case will be reviewed on October 25 but the couple are excused from attending.