The aim of this study was to bring new information regarding the feeding of one of the water frog species, Pelophylax ridibundus (marsh frog). Field surveys were carried out at 19 locations in 12 Iranian provinces. We examined the food composition of the marsh frog, throughout the distribution rang in Iran. The stomach contents were collected by using the stomach flushing method, stomach contents of 129 (68 males, 61 females) adult individuals were investigated, and 738 preys pertaining to nine prey classes were detected, predominantly terrestrial, within the diet of a P. ridibundus population. It was found that the species mainly fed on invertebrates; the most important prey taxa occurring in the diet were Arthropoda (91.77%). Among Arthropoda, the Insecta are remarkable for their wide presence in the stomach contents (79.87%). The average number of preysindividual was 5.68, while the maximum number of preyindividual was 43. There are no differences in size and diet between sexes and among the populations examined, but variation in diet among all localities clearly observed.
