Updated project metadata. Besides modulation of reverse cholesterol transport, high density lipoprotein (HDL) is able to modulate vascular function by stimulating endothelial nitric oxide synthase. Recently, it could be documented that this function of HDL was significantly impaired in patients with chronic heart failure (CHF). We investigated the impact of HDL proteome in CHF patients. Therefore, HDL was isolated from 5 controls (HDLhealthy) and 5 CHF patients of NYHA-class IIIb (HDLCHF). Proteome of HDL particles was performed by two-dimensional liquid chromatography mass spectrometry (SCX/RP LC-MS/MS). In total, we identified 494 distinct proteins, of which 107 proteins were commonly found in both groups (HDLCHF and HDLhealthy) indicating a high inter-subject variability across HDL particles. Several important proteins (e.g. ITGA2, APBA1 or A2M) varied in level. Functional analysis revealed intracellular regulated pathways. A minor proportion of bacteria-derived proteins were identified in the analyzed HDL-particles. The extension of the list of HDL-associated proteins allows beside their mere description new insights into alterations in HDL function in diseases. In addition, the detection of bacterial proteins bound to HDL will broaden our view of HDL not only as a cholesterol carrier but also as a carrier of several regulating proteins and even bacterial proteins.