Animals transgenic (Tg) for reporter genes would be useful to following a given cell lineage during differentiation and regeneration processes. Here, we established a beta-galactosidase (lacZ) Tg rat to use as a tool for regenerative research. Strong lacZ expression was observed in the skeletal muscles, myocardium, pancreas, and skin obtained from these lacZ-Tg rats, and moderate lacZ expression was observed in the liver, spleen, kidney, and cartilage. In contrast, brain, vessels, lung, adrenal gland, small intestine, blood leukocytes, bone marrow (BM) cells, and peripheral blood cells showed no lacZ expression. To test whether this lacZ-Tg rat could be used for regenerative research in myocardium, we induced myocardial injury after a lacZ-Tg BM transplant (BMT) into wild-type rats. The results show that lacZ-positive cardiomyocytes were found in the peri-infarct and uninjured myocardium in the BMT recipient rats. These findings suggest that lacZ-Tg rats are useful tool for regenerative research in the myocardium.