Background: Aquatic insects are able to transit the pathogens and disturb human beings. So, this study was performed to determine the type and distribution of insects in Kashan during 2001-2002.

Materials and methods: This is a descriptive study, in which 2222 larva and mature insects were collected from pools and stream habitats. After transporting to laboratory, they were diagnosed using morphologic diagnostic clues.

Results: The frequency of different types of insects was as following: Diptera 55%, Trichoptera 24%, Heteroptera 8%, Ephemeroptera 7%, Coleoptera 3% and Odonata 3%.

Conclusion: Considering the role of insects in transmitting pathogens and their disturbance for human beings, it is recommended further specific studies using molecular methods.