['To characterize the expression profiles of genes in purified monocytes from septic patients during systemic inflammatory response syndrome (SIRS) and compensatory anti-inflammatory response syndrome (CARS), and then to investigate the potential mechanism of monocyte deactivation.', 'Lipopolysaccharides (LPS)-induced cytokine responses, phagocytosis assay and migration assay were performed in monocytes from SIRS patients, CARS patients and healthy volunteers (n = 8). After functional assays, each pair of samples from the same group was pooled into one for gene expression analysis. All new samples (n = 4) were hybridized on NimbleGen human gene expression 12 × 135 K microarrays, and selected genes were validated by real-time polymerase chain reaction. Pathway analysis and Gene Ontology analysis were performed on differentially expressed genes using Agilent GeneSpring (version 11.0).', 'A set of genes related to pro-inflammation, phagocytosis, chemotaxis, antigen presentation, and anti-apoptosis were significantly down-regulated, while some genes associated with pro-apoptosis and anti-inflammation were up-regulated instead on monocytes from CARS patients compared with SIRS patients and healthy volunteers. Monocytes from CARS patients showed impaired production of TNF-α and IL-6, and increased release of IL-10 when stimulated by LPS. Functional analysis confirmed reduced phagocytosis and migratory activity of monocytes from CARS patients. Human leukocyte antigen-DR (HLA-DR) measurements demonstrated decreased expression of HLA-DR on monocytes from CARS patients.'] Does gene expression profiling reveal the defining features of monocytes from septic patients with compensatory anti-inflammatory response syndrome?