Frailty is a state of critically impaired homeostasis that results in heightened vulnerability to stressors. It is common in older persons and associated with adverse health outcomes. We have focused our attention on two different frailty systems, the first group of subjects affected by cardiovascular disease and the second one by Alzheimer's Disease. It is believed that cells with regulatory functions play a central role in the control of autoimmunity and inflammation. In our study we have analyzed the expression of T regulatory cells (TREGs), identified as CD4+, CD25high, FOXP3+ performing it on healthy, AD patients and cardiopath elderly people, using as control a group of young subjects. We have observed a progressive increase of these regulatory cells in the last one group and so it is very interesting if we considered that Treg expression do not present any significant differences between young and healthy old donors. We have evaluated Treg phenotype focusing our attention on the expression of FoxP3 in these three groups but no differences were observed. We have also related the NK number to Treg cells in the three groups. Our data show that in the cardiopath subjects we have a significant decrease of NK cells, but this result is not observed in AD patients. The reduction of NK cells is not surprising as NK cells are considered marker of successful aging. The meaning of the other results will be discussed.