Cadmium is toxic to a wide range of organisms; the main effects are on the growth and reproduction. Dissolved cadmium salts released in drainage water from mines may represent a significant threat to aquatic wildlife. Reproductively active aquatic animals exposed to pollutant stress undergo alterations in their biochemical and physiological functions leading to the disturbed reproductive processes. Biochemical constituents and enzymes are the first detectable / quantifiable responses to environmental changes and can serve as markers for both exposures and effects in organisms. In the edible crab Scylla serrata, the protein, carbohydrate, lipid, marker enzymes and antioxidants have been estimated in the ovary, hepatopancreas, muscle and haemolymph during various stages of the ovarian maturation. The results revealed there were declined levels of protein, carbohydrates, lipid and antioxidants in the cadmium reared crabs when compared to the control. The marker enzymes were increased in the haemolymph. The results were tested statistically and concluded that Cadmium toxicity has significant role in re-productivity.