B-type natriuretic peptide (BNP) is a hormone mainly secreted by cardiac ventricle myocytes and which is increased in cardiac diseases. Moreover, BNP expression has been shown in various cell/tissue types. Six different human endothelial cell (EC) culture models arising from macro and microcirculation either primary cultures or cell lines were cultured and screened for BNP presence and secretion. All cell types expressed BNP mRNA while only the ECs arising from bone marrow stromal compartment secreted high amounts of BNP protein. This report is the first to identify ECs as a new source of BNP. However, BNP secretion is limited to a particular EC type.