Film critic Bosley Crowther of The New York Times greatly enjoyed the movie, calling it "The broadest and funniest farce to come out of Hollywood since the Russians came last year...who would imagine that a film pretending to be a how-to on infidelity would be funny or even in good taste?" and adding "what is thoroughly and delightfully disarming about this mischievous film is the impudent candor of it and its freedom from the leer." The staff at Variety wrote in their review: "Walter Matthau plays a married innocent, eager to stray under the tutelage of friend and neighbor Robert Morse.
But this long-married hubby is so retarded in his Immorality (it takes him 12 years to get the seven-year-itch) that, between his natural reluctance and mentor Morse's suggestions (interlarded with warnings against hastiness), he needs the entire film to have his mind made up." Film critic Roger Ebert of Chicago Sun-Times wrote in his review: "There are a lot of funny people in this movie, but they are not very funny people in this movie, Gertrude Stein might have said. The Casino Royale syndrome has struck again in A Guide for the Married Man, and we are forced to sit and watch as dozens of big-name stars jostle each other for their moment before the cameras."