Makropulos Affair, The, is an opera in three acts by the Czech composer Leos Janacek (see Janacek, Leos). Its Czech title is Vec Makropulos. The composer himself wrote the libretto (text), which is based on a 1922 play by Karel Capek, a pioneer in what is now called science fiction (see Capek, Karel). The opera received its first performance at Brno, now in the Czech Republic, on Dec. 18, 1926.