Using high velocity particle bombardment, we transferred a reporter gene into early stages of the oyster Crassostrea gigas and showed the expression of the introduced genes in these embryos at later stages of development. We tested two promoters: (1) the heat shock protein 70 promoter of Drosophila; (2) the cytomegalovirus early promoter, both linked to the luciferase reporter gene. The hsp 70-luc (pDrluc) construct allowed an expression level up to 55-fold higher than the control in a heat inducible fashion. The CMV- luc (pCMVL) construct constitutively gave a 4-fold higher expression than the control. This confirms the suitability of particle bombardment for transfecting genes into eggs, zygotes and trochophores of bivalves and demonstrates the functionality of two heterologous expression vectors in C. gigas.