Most of the techniques related to part family formation require precise numerical data for part’s features. However, in many situations, the parts features are too ill- defined and are too susceptible to analysis by traditional discrete methods. Fuzzy set theory allows the parts to belong to different groups with different memberships. Moreover, different attributes may not have equal importance. The AHP (analytical hierarchy process) model gives the weightage for different attributes and also checks the consistency of the judgements. This paper suggests two models for part family formation using fuzzy mathematics and the AHP model. One model is based on fuzzy logic and AHP and the second model uses fuzzy equivalence ratios and AHP. Models can be integrated with the existing coding systems used by organizations. Both models are validated using problems from literature. © 2004, Taylor & Francis Group, LLC. All rights reserved.