Cardiovascular diseases are associated with multiple changes in gene expression. In general, cardiac tissue is not accessible to expression analysis. This study was designed to investigate expression of cardiac significant genes in white blood cells of heart failure patients and to identify differentially expressed genes. The quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) method was used for quantification of messenger RNA (mRNA) transcripts in blood samples of 20 patients (NYHA III-IV) with severe heart failure and of 20 healthy controls (NYHA I). Total RNA was extracted from leukocytes, reverse transcribed into cDNA, amplified and quantitated by SYBR Green detection. Relative mRNA expression was calculated using phosphoglycerate kinase-1 ( PGK-1) gene expression as an endogenous reference. Identified were 14 genes relevant to cardiomyocyte excitability or contractility. Most of them had not been previously reported to be expressed in blood cells. Data was based on 0.5 micro g total RNA applied to RT-PCR and on leukocyte number. In both, an increased transcription level of the Na/Ca exchanger ( NCX) was found in blood of heart failure patients as compared to controls (p < 0.02), in line with an upregulated NCX expression known from myocardial tissue of heart failure patients. This pilot study demonstrates that NCX transcription increased in potential relation to heart failure disease.