This book constitutes the thoroughly refereed post-proceedings of the 6th International Conference on Implementation and Application of Automata, CIAA 2001, held in Pretoria, South Africa in July 2001. The 23 revised full papers presented together with an invited paper were carefully selected during two rounds of reviewing and revision. The topics addressed from theoretical as well as application-oriented viewpoints range from foundational and methodological issues to novel applications in object-oriented modeling, finite transducers in natural language processing, and non-deterministic finite-state models in communication protocols.