The study re-evaluated the status of encysted metacercariae (EMC) of Family Heterophyidae in fresh and brackish water fish in an endemic focus in Egypt, as well as to study their morphological pattern. Seasonal variation of EMC was matched with their prevalence and intensity in infected fish. The study covered a period of one year from first of April 2011 to end of March 2012. The total percent of infection in the examined fish was 71.9% and 42.6% for brackish and fresh water respectively. The highest prevalence of the recovered EMC in both sources of water was for Heterophyes heterophyes (57.9%), followed by Pygidiopsis genata (39.7%), other Heterophyes spp. (21.09%), Haplorchis pumilio (19.5%), Phagicola spp (19.5%) and Stictodora tridactyla (6.2%). The highest mean intensity of the recovered EMC in both sources of water was for Pygidiopsis genata (10.27±2.83), followed H. heterophyes (9.45±7.13), Haplorchis pumilio (1.76±2.03),
Phagicola spp. (1.59±1.71), other Heterophyes spp. (0.82±0.99) and Stictodora tridactyla (0.48±0.92). By using ANOVA test, there was significant difference in sizes of EMC of Pyigidiopsis genata (P=0.04) and Phagicola spp. EMC (P=0.03) in comparison to corresponding ones in all fish species. By using Student T-test, there was significant higher size of Haplorchis pumilio EMC in Tilapia species in comparison to the corresponding one in Mugil species. Monthly variation showed that summer was the season with the highest prevalence and highest mean intensity of EMC in both brackish and fresh water fish. Also, undifferentiated EMC most properly of genus Centrocestus was demonstrated.