The present study was conducted to clarify the ole shellfish as a source for transmilling some parasiles of zoonotic importance for this purpose a total of 2181 shellfish sample representing 1151 fresh water crayfish (procambarus clarkia) . 534 white shrimps ( penaeus seliferus ) and 496blue crabs ( callinectes sabidus ) were collected from skarkia El- ismalia and port said proveinces and examined for the presence of trematode metacercariae and protozoal oocysts or cysts the results revealed that the infection rates of encysted metacercariae in the examined shellfish were 79.93% 52.06% and 38.7% in crayfish shrimps and crabs respectively the encysted metacercariae recovered from crayfish were belonging to four families of heterophyidae microphallidae cyathocotylidae and echinostomatidae the infection rates of encysted metacercariae in shrimps in sharkia Elismalia and port said provinces were 48.76% 54.04% and 52.87% respectively the obtained metacercariae were belonging to three families of heterophyidae microphallidae and cyathocotylidae the rates of crabs in fection with unidentified encysted metacercariae were 28.28% 43.9% and 42.85% in sharkia El- Ismalia and port said provinces respectively regarding the seasonal prevalence of encysted metacercariae in examined crayfish the peak of infection (93,79%) was detected in winter (27.27) one hundred and fifty six adult worms of ten trematode species were developed after experimental infection of sixteen puppies with different type metacercariae from metacercariae infecting crayfish 82 adult trematodes were developed where heterophyes aequalis pygidiopsis summa