A transgenic organism contains genes introduced from another species. The gene is called a transgene, and it is inserted into the organism's genome using genetic engineering techniques. Transgenic organisms are used in research, medicine, and agriculture. They are one type of genetically modified organism, but the term is often used interchangeably.

The first transgenic mice were created in the 1980s. Since then, transgenic animals have been used to study gene function, model human diseases, and produce therapeutic proteins. Transgenic goats produce antithrombin in their milk. Transgenic chickens produce eggs with proteins for drug manufacturing. Transgenic plants dominate global agriculture: corn, soy, cotton, and canola engineered for insect resistance or herbicide tolerance.

The technology has become more precise. Early methods inserted genes randomly, which could disrupt other genes. CRISPR and other editing tools allow targeted insertion at specific locations. This reduces unintended effects and improves predictability. The efficiency varies by species, and some organisms are harder to engineer than others.

Transgenic organisms raise regulatory and ethical questions. Who owns the intellectual property? What are the environmental risks? Should transgenic animals be used for food? The answers vary by country and by organism. The technology is powerful, and the debate is ongoing.