Letby, 31, repeated "not guilty" 18 times at Manchester Crown Court as the charges were put to her over a videolink from HMP Peterborough where she is on remand.
Letby is alleged to have murdered five boys and three girls while working at the neonatal unit of Countess of Chester Hospital.
She is also accused of the attempted murder of five boys and five girls, all alleged offences committed between June 2015 and June 2016.
After entering her pleas, the defendant, of Arran Avenue, Hereford, sat listening to hearing, which dealt largely with administrative matters.
A provisional trial date has been set for October next year.
Police launched a probe after the hospital raised concerns at the high number of deaths between March 2015 and July 2016 - which were said to be 10 per cent above average.
An internal inquiry was undertaken when medics found premature babies had died following heart and lung failure.