This article presents arguments that the first passion prediction in Mk 8.31 is part of an authentic core lying behind Mk 8.31-33. The author will demonstrate that the objections raised against the authenticity of the first passion prediction are weakened considerably when subjected to close scrutiny. Nothing demands that one designate it as a vaticinium ex eventu; it lacks that which one would expect to find if it were a creation of the early church; and there is no plausible tradition-history that accounts for Mk 8.31-33. On the other hand, the arguments in favour of its authenticity are quite convincing. Jesus elsewhere is aware of and vocal about his impending death; the prediction is the fulcrum upon which highly embarrassing elements of Mk 8.31-33 rest; Mk 8.31-33 is likely independently attested in Mt. 16.21-23; and the most economical and comprehensive explanation as to the origin of Mk 8.31-33 is that the historical Jesus predicted his death. The author will not address the authenticity of Jesus' prediction of his resurrection, and, therefore, it will not be included here as part of the authentic core of Mk 8.31-33.