In a context of fast socio-economic transition, the primary role of towns on rural change is to question. By endeavouring to free ourselves of ideological baggage (rural or urban bias), this paper is an attempt to measure the extent of periurbanisation that has taken place in Tamil Nadu. This work is based on geographical data, based on the 1991 census for Tamil Nadu and Pondicherry. The author undertook a systematic exploration of the relation between the 225 urban areas and the 16,085 villages of Tamil Nadu in order to estimate the influence of the urban areas on the surrounding villages. After re-examining the definition of urban areas, this paper underlines the diversity of periurbanisation, not only according to the type of town, but also on the basis of accessibility to these towns.