Particle bombardment is a physical method of cell transformation. This method can be used in high density cell number. It is a versatile and effective transformation method, not limited by cell type, species or genotype. There are no intrinsic vector requirements so transgenes of any size and arrangement can be introduced, and multiple gene cotransformation is straightforward. A major advantage of particle bombardment is that the delivered DNA can be manipulated to influence the quality and structure of the resultant transgene loci. Particle bombardment can be applied effectively for genetic transformation in seaweeds, such as: Ulva pertusa, Laminaria japonica, Undaria pinnatifida, Kapaphycus alvarezii, Porphyra yezoensis, P. tenera, P. okamurae, P. onoi, P. variegate, P. pseudolinearis, Gracilaria gracilis, and G. changii. Gene expression in the transformation of seaweed using particle bombardment can be transient and stable. Based on their gene expression status, suggesting that genetic transformation using particle bombardment technique can be applied in seaweed.