 American film critic Andrew Wickliffe considered the lead up to the appearance of the monster to be more interesting than the rampage that follows, writing, "I'm not sure the British are really suited for giant monster movies.No offense to the Brits, but watching a bunch of folks stand around and keep the stiff upper lip while radioactive monsters from the deep attack London isn't too much fun".Regarding a later release of the film in a package with other science fiction features, film reviewer Glenn Erickson observed that "The Giant Behemoth" was derivative, speculating that "... director Eugène Lourié apparently instructed writers Robert Abel and Alan Adler to repackage his original "The Beast from 20,000 Fathoms", copying whole scenes and situations.