Tehran, the capital of Iran came under the invasion of rats. Experts have found that amount of rats exceeded 50 million. The Tehran earthquake and the mice problem that appeared recently has become the second major problem after air pollution for residents of Tehran. Millions of rats inhabits the city and this number continues to increase every day. Tehran municipality is fighting the rats, they concluded it to be Norwegian rats. According to statistics provided by Iranian experts, at least 50 million mice live in Tehran. They also say that the methods used to control the number of Tehran rats are insufficient. Experts have suggested that the mice are evolving. Tehran rats are no longer afraid of humans or cats therefore are not running away. It is stated that the reason for the multiplication of the mice is the garbage that is thrown into the streets.