It stars John P. Ryan and Sharon Farrell as a couple whose infant child turns out to be a vicious mutant.

The film's cast also includes James Dixon, William Wellman Jr., Shamus Locke, Andrew Duggan, Guy Stockwell, and Michael Ansara.

The baby was designed and created by special effects make-up artist Rick Baker, and the film's score was composed by Bernard Herrmann.

Frank meets with medical researchers who convince him to sign documents allowing them to experiment on the child's body once it has been found and killed.

Wrapping the baby in his coat, Frank tries to elude the police, but a mob of armed cops confronts him as he exits the sewers.

As the grieving Davises are escorted away by the police, a depressed Lt. Perkins receives news that another similar mutant baby has been born in Seattle.

Special effects make-up artist Rick Baker designed and created the murderous baby depicted in the film.

[6] Cohen had decided to rarely show the infant in the film, and asked Baker to create a "dummy baby" for the actors to react to.

The site's critical consensus reads, "Tough and unpleasant, It's Alive throttles the viewer with its bizarre mutant baby theatrics.

[9] Vincent Canby of The New York Times wrote, "Mr. Cohen is not unintelligent, but the few interesting ideas in his horror films, including the recent Demon, are drenched in supreme silliness by way of the dialogue and special effects.

[12] Kevin Thomas of the Los Angeles Times called it "a sort of primitive low-budget sequel — rip-off may be the better word — to Rosemary's Baby.

Despite patches of risible dialogue and other ludicrous bits and pieces it holds attention and even manages to be pretty scary.

"[14] Leonard Maltin gave It's Alive two-and-a-half out of four stars, commending Herrmann's score but noting that the film is "not for all tastes.

"[16] A review published by Time Out reads, "Despite such potentially sidesplitting material, the film often manages to instill a genuinely chilling atmosphere, with its initially kitsch family growing into human beings as they plummet into a world unhinged and apart at the seams.

"[17] Dennis Schwartz of Ozus' World Movie Reviews gave It's Alive a grade of "A," praising Ryan's performance and calling the film "a wacky low-grade entertaining horror pic, one that also has an edge, is discomforting and surprisingly has a good blend of humor and splatter.