Psoriasis is a chronic inflammatory skin disorder associated with a host of immune abnormalities. We have recently proposed that psoriasis is related to aberrant hematopoiesis and hypothesized that aberrant hematopoiesis in psoriasis is due to the differential hematopoietic microenvironment. To investigate whether the hematopoietic microenvironment is altered in patients with psoriasis by comparing the levels of cytokines secreted from BMSCs in patients with psoriasis and those in healthy volunteers, flow cytometry analysis was used to examine the proportion of the positive cells and direct ELISA was used to measure the concentrations of cytokines secreted from BMSCs in patients with psoriasis and healthy volunteers. In comparison with normal controls, BMSCs from patients with psoriasis showed increased secretions of SCF, G-CSF, and IL-6, decreased secretions of IL-1alpha, IL-1beta, IL-3, IL-8, EGF, VEGF, TNF-alpha, LIF, HGF, PDGF and no alteration in the levels of GM-CSF, IL-11, IL-7 and the cell surface markers CD29, CD34, CD45 and HLA-DR. Our data demonstrate for the first time that the hematopoietic microenvironment is altered in patients with psoriasis, suggesting that an aberrant hematopoietic microenvironment may be one mechanism for the pathogenesis of the disease.