Problem statement: Hygiene and purification are very important in the religion of Islam. The importance is manifested more in paying attention to a type of architecture namely bathroom. Bathrooms, in addition to physical and material characteristics, have ritualistic and immaterial characteristics and in order to identify them, common physical structure of public should be studied. Of course, it should be noted that these structural patterns in architecture and particularly in traditional architecture have direct relationships with building functions and in fact, any building is constructed for special function and with a pattern appropriate to it. One of the main functions of bathroom is to perform rituals of purification and according to most researchers; rituals of the purification are of rites of passage. Now the question arises that what role did rite of passage play in the physical structure of Iranian public baths? Reaserch objectives: The present study has emphasized to find the effect of rites of passage on basic pattern of Iranian public baths. The results of the present study show that the threepart structure of rites of passage was considered as an inspirational concept in the design architecture of the bathroom. Research method: In order to study the role of rite of passage in physical structure of Iran’ s public baths in accordance with the research requirements, while using the logical reasoning based investigation, historical interpretation method is also used. The research data have been gathered via library resources and documentary studies. Conclusion: Iranian baths have three-part structure including a Bineh (caldarium), a mediator (middle corridor) and a hot chamber (tepidarium) and purification as the main function of bathhouses reflects the rite of passage. In general, rite of passage has three separate, purgatory and reintegration stages and this three-stage spiritual journey can be seen in bathing customs and purification rituals. The results of the present study show that three-part structure of passage is likely the inspired concept of traditional structure in architectural design of bathhouse and the use of three-part structure in its body.