The Gilan territory is situated at the north of Iran, between Alborz Mountains and the Caspian Sea. The natural features of this territory are essentially are an extensive combination of the west Alborz mounts and the coastal plains of the Caspian Sea, thus having an eternal magnificent statue. This territory, due to its natural conditions, has suffered from natural disasters including earthquakes, floods and land mass movements, even in recent centuries. The combination of these natural factors as the basic cause, unintelligent human intervention as an intensifying enforcer, has resulted in “landslides” in many parts of the Gilan territory. In this paper, after introducing the Gilan territory with its geographical and natural particularities in Iran, care has been taken to discuss a number of important points including the effect of natural factors in developing the land slides, the impact of unintelligent human intervention as a reinforcing element, disturbance of the environmental balance and the impact of these landslides on the environment.