Forensic entomology is a branch of forensic science that uses knowledge about insects and other arthropods when researching various cases involving human remains mainly because it is possible to determine the post mortem interval based on their life cycle. Carnivorous species of flies belong to a group of forensically important insects because it is possible to determine the post mortem interval based on their life cycle. Post mortem interval gives us the time interval in which the death most likely occurred. Since the post mortem interval is affected by many abiotic and biotic factors of the environment, one can never give exact time of death but rather the interval in which death occurred. The aim of this study was to compare the number and diversity of carnivorous species of flies that can be found in the areas of city of Split and on the island of Vis during spring months in 3 separate experiments with 40 days apart from each other. It was also important to establish whether the abundance and diversity of carnivorous fly species was based on differences in environmental habitats such as plant composition, ambient temperature and humidity. The insect trap was made from plastic bottle that has a hole through which a fly enters the trap. At the top of bottle chicken liver was placed that would attract carnivorous type of flies and at the bottom of the bottle 70% alcohol was poured in in order to prevent the flies from coming out of the bottle and to preserve them for later analysis. Fly collection is followed by morphological identification using a microscope and an identification key. Based on proven research, it can be concluded that there is a difference in the number, but also in the diversity of carnivorous species not only on different locations, but also between different experiments done in the same location. The difference in the number of carnivorous species of flies between the two locations is primarily affected by the difference in the environment, but also by the difference in temperature and humidity, while the differences between experiments on same location are only affected by the difference in temperature and humidity. The number and variety of flies in the city of Split is much higher than on the island of Vis due to more favorable temperature and humidity. In addition, city of Split has more animal carcasses that decompose throughout the year, which means more food source for forensically important flies to feed on and hence greater numbers. It was expected that the number and variety of flies will 37 increase over the months on both locations, but due to unfavorable weather conditions that did not happen.