The production of transgenic animals was a great biotechnology revolution in the fields of science and health. Pig is a very important animal for the agriculture industry, but also it is an important lab animal used in models for biotechnological studies and human diseases. In the last 25 years, transgenic pigs have been improved by the development and application of new molecular biology and assisted reproductive technologies. In this manuscript we review the different methodologies used for producing transgenic pigs. We analyze the advantages and limitations that each methodology offers. We describe from the first studies for producing transgenic pigs by pronuclear injection to the latest studies with induced pluripotent stem cells (iPSC) recently described. We also analyze the used of virus, sperm mediated gene transfer and somatic nuclear transfer technology. Finally we contribute with our own experience developed in this amazing field of science by our research group during recent years.