In the Florida Everglades, a group of gigantic, intelligent leeches live secretly beneath the depths of a deep swamp.

Only a few days after, two more locals, Liz Walker (Vickers) and Cal Moulton (Emmet) go missing near the swamp, while having an affair behind the back of her husband (VaSota), who is wrongly blamed for their deaths (eventually committing suicide while in jail).

[2] The film was shot over eight days, including outdoor sequences at the Los Angeles County Arboretum and Botanic Garden.

[1] Actress Yvette Vickers had appeared as the Playmate centerfold in the July 1959 issue of Playboy magazine,[3] several months prior to the film's release.

[9] A review of the film in AllMovie described it as "uneven at best but the swamp locations, filmed at Pasadena's Arboretum of Tarzan fame, are certainly picturesque and the cave sequence, photographed, according to co-star Yvette Vickers, at the old Charlie Chaplin Studios, at least somewhat creepy," adding that the leeches are "stunt divers wearing what appears to be small ponchos with tentacles.

[13] In July 1992, Attack of the Giant Leeches was featured as a fourth-season episode of the film-mocking television series Mystery Science Theater 3000.

[16] The MST3K version of the film was released on October 26, 2004, by Rhino Home Video as part of a box set, The Mystery Science Theater 3000 Collection: Volume 6.