Delphi as a consensus development technique enables anonymous, systematic refinement of expert opinion with the aim of arriving at a combined or consensual position. In this study, we determined the criteria and their weights for Iranian Medical Schoolsʹ ranking through a Delphi process. An expert committee devised 13 proposed criteria with 32 indicators with their weights, which were arranged hierarchically in the form of a tree diagram. We used the Delphi technique to reach a consensus on these criteria and weights among the deans of 38 public Iranian medical schools. For this purpose, we devised and sent a questionnaire to schools and asked them to suggest or correct the criteria and their weights. We repeated this process in two rounds till all the schools reached an acceptable consensus on them. All schools reached a consensus on the set of 13 criteria and 30 indicators and their weights in three main contexts of education, research and facilities, and equipment which were used for Medical Schools’ ranking. Using Delphi technique for devising the criteria and their weights in evaluation processes such as ranking makes their results more acceptable among universities.