This is a critical reading of two Polish science-fiction novels of the post-Apocalypse subgenre, Cassandra’s Head by Marek Baraniecki and The Old Axolotl by Jacek Dukaj, with the help of concepts borrowed from the philosophical toolkit of Jacques Lacan. Each of the two books envisages an apocalyptic catastrophe and its consequences as well as the subsequent attempts to rebuild human civilization. The action in either novel is shaped by tensions between the Symbolic and the Real. The latter, though suppressed and shut out, keeps resurfacing, usually when it is least expected, leaving an indelible marks in the life of the survivors. An analysis of the handling of this conflict in the two novels offers a number of insights into the way these two fundamental modes (or, Lacanian orders) of human perception are integrated into the worlds of post-Apocalyptic fiction.