This book constitutes the refereed proceedings of the 8th International Workshop on Post-Quantum Cryptography, PQCrypto 2017, held in Utrecht, The Netherlands, in June 2017. The 23 revised full papers presented were carefully reviewed and selected from 67 submissions. The papers are organized in topical sections on code-based cryptography, isogeny-based cryptography, lattice-based cryptography, multivariate cryptography, quantum algorithms, and security models.