This volume constitutes the thoroughly refereed post-proceedings of the 6th International Workshop on DNA-Based Computers, DNA 2000, held in Leiden, The Netherlands, in June 2000. The 16 revised full papers presented together with two invited papers were carefully reviewed and selected from 33 submissions. All aspects of DNA computing, ranging from theoretical and foundational issues to algorithms, are addressed, from the computer science point of view as well as from the molecular biology point of view.