Wide fluctuations in the concentration of the haemolymph protein and its copper were observed during the moult cycle of the crabOcypoda macrocera. Blood protein and copper concentrations were more in the intermoult (C4) and premoult crabs (D1-D2) but decreased in the postmoult crabs (A1-B2). A direct relationship between the blood protein and copper concentration is observed during the moult cycle. More copper in the hepatopancreas is seen during the premoult stage (D1-D2) and its level increased further in the postmoult stages (A1-B2). Increase of hepatic copper with a decrease in haemolymph copper content during the post moult stages shows the transfer of copper liberated from the haemolymph to the hepatopancreas due to the breakdown of haemocyanin, the major blood protein, during starvation period of moult cycle.