The analysis of electrophorectically detectable protein variation has revolutionised population genetics and allowed the extent and structure of genetic variation in natural populations to be described. The method is now widely applied to determine the structure of exploited populations in order to identify the number of stocks in a fishery, or to determine the level of genetic variations in cultured polulations. This publication describes sample collection and storage, protein stability, electrophoresis and enzyme surveys in relation to giant clams and is illustrated with many figures.