This book constitutes the refereed proceedings of the 6th International Workshop on Knowledge Representation for Health Care, KR4HC 2014, held as part of the Vienna Summer of Logic, VSL 2014, in Vienna, Austria, in July 2014. The workshop aimed at attracting the interest of novel research and advances contributing in the definition, representation and exploitation of health care knowledge in medical informatics. The 12 revised full research papers and 4 short papers presented in this book were carefully reviewed and selected from 26 submissions.