Total protein, lipid and carbohydrate variations for the whole embryonic development were measured every 48 hours in samples of eggs of Macrobrachium occidentale (Holthuis), 1950, a small freshwater caridean. Proteins are the main component followed by lipids and carbohydrate only as minor constituent. Most required energy seems to come from metabolism of fat, which was profusely depleted during the whole of development while proteins seem to be mostly utilized for tissue formation. Details of morphological changes of every developmental step are also presented and a comparison of present results with works of other prawn eggs is discussed.