Embryos and larvae of the european lobster H. gammarus, reared under laboratory conditions, were investigated in order to determine the nature and metabolism of carotenoproteins during embryogenesis. Extracts of embryonic as well as larval stages were analysed, using DEAE-Cellulose filtration, electrophoresis, and thin layer chromatography. Ovoverdin is the main carotenoprotein of the yolk; two fractions, having different molecular weight (No1: 700 kDa and No2: 600 kDa) were observed. Larval extracts were found to contain three coloured carotenoproteins: blue (Lm1a), red (Lm1b), and yellow (Lm1c). Yolk carotenoids were identified as free astaxanthin and unesterified phoenicoxanthin, whereas esterified astaxanthin was found to occur in the forming tissues. Astaxanthin diester is the main carotenoid of the embryo; in larval tissues, this carotenoid is associated to the red carotenoprotein. The increase in esterified astaxanthin suggests enzymatic mechanisms leading to acylation reactions occurring at an early stage of embryonic development.