Lawyers for Ariel Castro entered the plea during a brief arraignment, CNN reported.
Castro, 52, was indicted last week on 329 counts.
Among the charges, he is accused of two counts of aggravated murder by purposely causing the unlawful termination of a pregnancy.
Police say one of the kidnapped women was made pregnant five times by Castro and another woman bore a child fathered by him.
He also is charged with 139 counts of rape, 177 counts of kidnapping, seven counts of gross sexual imposition, three counts felonious assault and one count of possession of criminal tools.
Only the first half of the 10 years the women were held hostage are covered by the indictment.
Michelle Knight, Amanda Berry and Georgina "Gina" DeJesus were freed last month after Berry yelled for help while Castro was gone.
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