In recent years, tenure security has been one of the main objectives of improvement projects in ‎urban poor settlements. Despite lots of international studies initiated in this field, it has received ‎little attention in Iran. The main aim of this paper is to assess the influence of tenure security on ‎the level of household investment in housing. Survey method is considered as the methodology ‎of this research hence questionnaires were prepared and filled in EslamAbad Neighbourhood of ‎Tehran, Iran. In this study, Legal, extra-legal, perceptive fear of eviction, and the probability of ‎eviction were four main indices used to measure tenure security with household income index as ‎a controller variable. The findings of the research showed that there is a significant relationship ‎between three different kinds of tenure security. In addition, it revealed that between five ‎indices used, only three indices (e.g. legal, household income and perceived fear of eviction) ‎affect the level of investment in housing by household. In comparison to other indices, fear of ‎eviction was the most important factor that affects tenure security.‎ تفاصيل المقالة