Numerous reports list the abnormalities obtained from cloning sheep and cattle. To date, few reports provide detailed information regarding the overall health status and performance data of cloned animals. This report follows three litters totaling 10 transgenic cloned piglets from birth through puberty. Significant findings from physical examinations and response to treatments are included, as well as necropsy data from five of the piglets that died during the study. The birth weights, placental weights, and growth rates for this group of piglets were not different from that of control animals raised in the same environment. Hematology and serum chemistry data were collected at 2 days of age, and at 2, 4, 8, 12, 16, 20, and 24 weeks of age. Results indicated a mild anemia and hypoproteinemia in the cloned piglets from birth through 4 weeks of age, but both conditions were corrected by 8 weeks of age. Echocardiography was performed on seven of the piglets. No anatomical defects were detected, but three of the piglets had decreased cardiac output values. However, both animals are growing and show no evidence of clinical disease. The immune system was evaluated by quantification of serum IgM and IgG levels and by determining the population of B-cells, macrophages, helper T-cells (CD4), cytotoxic T-cell (CD8), and double positive T-cells (CD4/CD8). With the exception of one animal, no abnormalities were detected with the immune system of the examined piglets. During the course of this study, five of the 10 piglets were euthanized or died, indicating there is a high mortality rate among cloned piglets, but the remaining five cloned piglets are free from detectable defects.