Objective: Children of the street is such a problem that concern many of contemporary societies, whether it is developed or underdevelopment. Method: This research had studied "children of street" phenomena in five big cities(Tehran, Mashhad, Ahvaz, Shiraz, Rasht) with surrey method. Findings: Research findings indicates that some factors includes, misconduct of socializing institutions such as families and schools, economic poverty of children's families and their disability in adapting and coping with big cities' way of life, pollution and pathos of marginal communities, not to being controlled by responsible organizations, and mischievous patterns of interaction between citizens and the children, all are working together to raising, spreading, and to be continuing of children of the street as an involving problem in many of our big cities.