The genus Acacia includes about 1250 species growing in tropical and sub-tropical regions of Australia, Africa, India and America. They are an important source of firewood, green manure, paper pulp, tannin and also contribute to soil improvement. Like most forest trees species, they have been propagated through seeds and improved by conventional breeding techniques. Recent developments in biotechnology have resulted in considerable progress in the propagation and genetic breeding of forest species. These techniques have been successfully applied to tropical species like, for example, Eucalyptus and Pinus, allowing high multiplication rates and homogenicity of the propagated material. However, up to now genetic transformation techniques have been mainly developed using the poplar, a species that grows in temperate cIimates, and with the papaya, a tropical fruit tree. This chapter provides a review of recent advances in tissue culture and genetic transformation of four tropical Acacia species: A. albida, A. crassicarpa, A. mangium and A. mearnsii.