We have successfully applied mouse transgenic technology to the rat, with appropriate developments in the techniques of ovulation enhancement (superovulation), microinjection, and embryo transplantation. We have generated transgenic rats possessing the mouse Ren-2 gene and have further characterized the expression of the transgene and the consequences of its expression. We find that the systolic blood pressure of male transgenic animals is elevated by the age of 5 weeks, and increases to a level of 230 mm Hg by 8 to 10 weeks. This level is maintained beyond 20 weeks of age. In control animals systolic blood pressure reaches a plateau of 140 mm Hg. Although the blood pressure is greatly increased in the transgenic rats, plasma renin activity remains suppressed over the same 20-week period. Morphologic studies reveal signs of cardiovascular damage caused by the hypertension, including diffuse thickening of the arterial media based on smooth muscle cell proliferation and connective tissue matrix neogenesis.