The Qajar era is of great importance in the socio-political history and in the history of architecture of Tehran, because it was in this era that Tehran became the capital of Iran and turned into a big city, and then, because of its specific architecture, paved the way for some great changes in the architecture of Iran. The Qajar era is a period of contradiction in architectural values and attitudes, and consequently, an era of diversity of trends, principles and methods in architecture and urbanization. These diversity and contradictions, which are the result of different domestic and foreign factors (such as the specific culture of the Qajar era, relationship with Europe, the influence of the foreigners, the feeling of inferiority to the West, the return of the Iranian architects who had studied in Europe, the presence of European engineers in Iran, the introduction of European styles of architecture, etc), different approaches of tradition and modernity and gradual changes in Tehran, are manifested in residential architecture more than anywhere else, and they engendered diversity and difference in the unvarying structure of houses in Tehran. This diversity is reflected in all parts and elements of houses, from the entrance spaces to the internal spaces; however, since the entrance space is a part of the façade and is highly conspicuous, the changes in this part are more tangible and the analysis of its structural and decorative characteristics, as key factors in the outward form of the city, is of greater importance. What is significant here is that although the aforesaid changes incorporate all elements and decorations of the entrance space, they exert the major influence on the entrance spaces of the houses of a group of people in society, and not only has the extent of this influence on the various details of entrances been quite different, but also its kind differs from one house to another house and from one neighborhood to another neighborhood. By analyzing these differences we might be able to sketch out some prominent features of different entrance spaces, and based on it, study the dominant style of the entrance spaces in different neighborhoods of Tehran, and, consequently, the residential architecture of city. For this purpose, the authors of this article conducted a field research and examined the houses built in different districts of Tehran in this era. In this study 80 Qajar houses were examined and documented in various districts of Tehran such as Udlajan, Chal Meidan, Bazar, Sanglaj, Arg/Dolat and, also, the northern districts of the city. After the initial study, 40 houses were selected to be fully illustrated in the table at the end of the article. It can be claimed that different styles are adopted in the entrance spaces of houses in Tehran of the Qajar era which, depending on the architecture of the house, time, location, local texture, and the social and economic status of the owner, are clear manifestations of tradition, modernity or a combination of both, with slight differences in their application.