Bacillus thuringiensis (Bt) is a gram-positive and spore-forming bacterium that produces parasporal inclusions containing Cry and Cyt proteins during sporulation. These inclusions or proteins are highly toxic to lepidopteran, dipteran, coleopteran larvae, and nematodes. Because of their selectable specificity and safety to non-target organisms and environment, Bt is considered as a valuable and safe alternative to chemical pesticides for eradication of insect pests. Bt biopesticide products has been commercialized and used very widely and successfully in agriculture, forestry and medical care markets since 1930s. In Korea, the screening for isolation of new Bt strains such as Bt Nt0423 (Tobbagi) and Bt GB-413 (Solbichae) have been performed and their commercial products were launched in agricultural markets. In terms of public health, mosquito larvicidal products made by Bt subsp. israelensis have been registered by Korean ministry of food and drug safety and used since 1995. Recently, a new mosquitocidal serovar (H3a3b3d), Bt subsp. mogi was isolated and its molecular characteristics were analyzed. In our opinion, Bt biopesticides might be still an effective and safe tool for insect pest control in agriculture and public health. Key words: Bacillus thuringiensis, biopesticide, Bt subsp. israelensis, mosqui