Don Siegel's screen version of Finney's novel, Invasion of the Body Snatchers (1956), is widely regarded as a masterpiece of low-budget filmmaking.

Critics credit this black-and-white movie (starring Kevin McCarthy and Dana Wynter) with demonstrating the cinematic potential of science fiction scripts. The movie altered Finney's narrative in two important ways. It allows Becky Driscoll to be taken over by her pod-clone, and it ends with Miles Bennell vainly warning others.

The film concludes on a note of desperation rather than with a tribute to human indomitability.

In 1978, Philip Kaufman remade Don Siegel's movie on a larger scale. Kaufman shot the film in color, switched the setting to San Francisco, and added an eerie score of electronic music. Although a good film in its own right, Kaufman's picture further departed from the contrast which had made Finney's novel so powerful: overwhelming horror in an idyllic small town.