Box office The film opened at number seven, grossing $2,066,980 in the opening weekend. It went on to gross $13,854,000 in the United States,
Janet Maslin, reviewing the film for
The New York Times, panned the film's screenplay and humor, as well as the performance of Dan Aykroyd, who she felt was not only miscast as the film's romantic lead, but also unfunny. However, Maslin praised the performances of Kim Basinger and Jon Lovitz, whose character she categorized as a "scene-stealing sleazeball". In a generally favorable review,
Kevin Thomas of the
Los Angeles Times criticized the film's sex humor, calling it "needlessly crass", but overall praised the film, writing, "
My Stepmother Is an Alien is solid, wide-appeal holiday fare. It makes the best use of Aykroyd's warmth and proven talents in quite some time, and it does even more for Basinger, showing that she can be as funny and smart as she is sexy." The
Radio Times gave the film three out of five stars, writing, "Fine moments of inspired lunacy jostle with predictably slight comic relief, but Basinger's eager-to-please freshness and verve make this intergalactic muddle impossible to dislike."
Variety called the film a "failed attempt to mix many of the film genres associated with the 'alien' idea into a sprightly romp."
TV Guide gave the film one star, calling it "A standard formula comedy [which] tries to emulate popular alien-on-Earth films like
Starman. Had it actually been told from the perspective of the scientist's daughter, as the title suggests, it might have been more appealing, but instead a predictable, amateurish script shifts the focus elsewhere." Writing in
People,
Peter Travers said that director Richard Benjamin "tries to disguise the threadbare plot with explosions and special-effects hardware", and called the film "a clanking bore, except for Basinger—a potential star still waiting for the vehicle that will let her shine. Her comic talent glimmers in a scene where she learns what a kiss is."
Time Out wrote, "The film offers several entertaining sequences, [but
My Stepmother Is an Alien] is marred by cruel and juvenile gags." On
Rotten Tomatoes, the film has a score of 20% based on reviews from 25 critics, with an average rating of 4/10. The consensus states: "Kim Basinger is otherworldly funny in this harebrained sci-fi rom com, but she still can't save
My Stepmother Is an Alien from alienating intelligent earthlings." On
Metacritic, the film has a weighted average score of 47 out of 100 based on 14 critics, indicating "mixed or average reviews". Audiences surveyed by
CinemaScore gave the film a grade "B−" on scale of A to F. ==Namesake==