apparatus for blow molding hollow plastic bodies comprising a plurality of pairs of mutually joinable half - molds capable of being opened and closed , associated to an appropriate rotary apparatus carrying said half - molds , a retrieval device adapted to remove the finished container from the respective pair of half - molds after the opening thereof , an opening and closing mechanism adapted to close the half - molds after the passage thereof through the position of the preform feeding mechanism , and to open them before the passage thereof through the position of the finished - container removal mechanism , in which said pairs of half - molds are constituted by a fixed half - mold and a moving half - mold that is capable of being opened from and closed against said fixed half - mold . in a preferred manner , said fixed half - molds are linked to said rotary apparatus and are arranged in a substantially vertical position , with the respective moving half - mold adapted to be closed by accomplishing a substantially rotary movement about a horizontal axis of rotation .