Filter feeder shellfish are mostly present close in shore and are therefore liable to contamination from sewer effluent, discharges from shipping, house boat, etc. So, they accumulate and concentrate pathogenic microorganisms. Harvesting of shellfish from polluted areas constitutes a major public health hazard. Regarding that oysters are traditionally eaten raw or mildly cooked, and the whole animal is edible rather than only the muscle, they seem as being such a high risk food that is widely associated with food poisoning. Several outbreaks were reported worldwide associated with ingestion of contaminated oysters. As a result studies of shellfish should focus on public health hazards associated with consumption of contaminated seafood since microorganisms may remain viable within oysters for long periods. The study highlights the effect of the harvesting season on the sanitary condition of Crabs, Gandoffli and Om El-Kholoul harvested from different Egyptian coasts and identifies the microorganisms of public health hazard as well. Food microbiologists, food hygiene researchers, seafood producing establishments, and people interested in shellfish are invited to read the book.