The aim of this thesis is the determinations of insects species of forensic importance in Kayserı province. The experimental part of our study was carried out between September 2018 – May 2019; during the periods of winter, spring, autumn seasons in four different regions. In this study, fresh cow liver and chicken muscle were used as the experimental materials. The traps which allow the insects to enter easily but which prevent exit were used to collect insect species. As a result, 21 species were identified in four different study areas. Calliphora vicina (Robineau-Desvoidy, 1830) (Diptera: Calliphoridae), Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae), Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae), Muscina stabulans (Fallen, 1817) (Diptera: Muscidae), Musca autumnalis (De Geer,1776) (Diptera: Muscidae), were identified in fall season at all study areas. C. vicina was identified in winter season. C. vicina, Thricops sp. (Rondani, 1856) (Diptera: Muscidae), Fannia canicularis (Linnaeus, 1761) (Diptera: Fanniade), L. sericata, Dermestes frischii (Kugelann, 1792) (Coleoptera: Dermestidae), were identified in spring season at all study areas. C. vicina was seen from September to the end of May at all study areas. L. sericata was seen from September to the end of November and April to end of May at all study areas. Therefore, C. vicina and L. sericata can be used as an indicator species for determining the Postmortem Interval in Kayseri.