The early half of the last century has witnessed a great attention to family Heterophyidae especially in Middle and Far East since infecting both man and animals. Seasonal variation concerning prevalence and intensity of fish infection. Fish specimens were collected from highly endemic region in Alexandria governorate during summer and spring seasons. Encysted metacercariae were identified and used in subsequent experimental infection of laboratory mice was carried out to allow morphological identification of eggs and adult worms. The prevalence of infection was much higher in summer (90.10%) than in spring season (54.76%).P.genata has proved highly infective, since all experimental mice had acquired infection. Morphological characteristics may help distinguish P.genata stages from other heterophyids