This research reviews factors affecting product class involvement in industrial-bread-purchasing behavior. Model of this paper is based on the conceptual model presented in Drichoutis & et al's study (2007). Their recommendations and suggestions have been planned and developed for future researchers. Product class involvement is measured by five factors: taste, price, nutrition, ease of preparation, and brand name. The research method is descriptive and our data is gathered by questionnaire tool and survey method. Statistical universe of this study is buyers of Industrial-bread in Tehran metropolitan and 404 samples choosed by multi stage cluster sampling. Using Generalized Linear Models (GLM), data have been analyzed. Firstly, the model accuracy has been verified by chisquare test. And magnitude of Cox and Snell, Nagelkerke and McFadden indexes showed the appropriate status of Model Fitting After that by examining the amount of probability of eath variables in 95% Confidence Level, hypothesizes “education”, “income”, “household size”, “main meal planners”, “follow certain dietary guidelines”, “believe what one eats can reduce the risk of getting a disease”, “spend more time looking for nutritional information” is supported and influence of “nutrition knowledge”, “major grocery shoppers”, “special diet status”, “time spent grocery shopping”, “working Status”, “ family life cycle” is not supported.