Abstract: A rotating blowout preventor apparatus includes an adaptor located at the upper end of a main body, and a rotating head assembly which is removably received by the adaptor. The adaptor is longitudinally split to provide two segmented circles which are hinged together, and which may be opened to thereby enable a very large bit to be received within the main body. The rotating head assembly is left affixed to the drill string, with the bit located in underlying position respective to the rotating head assembly. Relatively small rotating blowout preventors can accommodate extremely large drill bits by utilizing the present invention.