Bosley Crowther of "The New York Times" wrote, "After all the spy and mystery movies of a romantic and implausible nature that we have seen, it is great to see one as realistic, and believable too, as 'The Spy Who Came In from the Cold.'" "Variety" called the film "an excellent contemporary espionage drama of the Cold War which achieves solid impact via emphasis on human values, total absence of mechanical spy gimmickry, and perfectly controlled underplaying." Philip K. Scheuer of the "Los Angeles Times" wrote, "It is not an easy, certainly not a pleasant, picture to sit through; too impersonal, too objective, to move us to weep, so that its ending can only leave us tremendously depressed." Richard L. Coe of "The Washington Post" declared, "Not having shared the evidently widespread admiration for 'The Spy Who Came In from the Cold' in its original form as a novel, I nonetheless find it a wholly absorbing picture." Brendan Gill of "The New Yorker" called it "in every respect an admirable translation the screen of the fantastically popular thriller by Jean ["sic" le Carré." "The Monthly Film Bulletin" wrote, "Concentration is demanded; and earned by the tension and accuracy of the dialogue and the high level of performance ... cast all give performances of a kind which instantly engage attention, even if the characters scarcely develop beyond the point at which we first meet them."