Background: The local production of cytokines and phagocytosis is pivotal in innate immunity. Uremic patients have a high infectious morbidity, but it remains unclear if this arises from incompetence of these local cellular functions. Methods: In 30 predialysis uremic patients and 20 controls, we studied the intracellular cytokine synthesis by mononuclear cells in response to stimulation. Moreover, phagocytic activity by leukocytes was tested. Lipopolysaccharide- or mitogen-stimulated peripheral blood cells were labeled with anti-CD14 and -CD4 antibodies, respectively and subjected to intracellular cytokine staining and flow cytometry. Tumor necrosis factor (TNF)-α, IL-1β, IL-6, and IL-8 synthesis was examined in CD14<sup>+</sup> monocytes. IFN-γ and IL-4 synthesis was examined in CD4<sup>+</sup> helper T cells to determine their Th1 or Th2 phenotype. The flow cytometric analysis of phagocytosis of opsonized bacteria was performed in whole blood. Results: Uremic patients exhibited a significantly reduced monokine response and inhibited development of helper T cells into Th1 or Th2 phenotypes compared with control subjects. Their phagocytic activity was comparable to control subjects. No clinical parameters were linked to in vitro cytokine production and phagocytic activity. Conclusions: Mononuclear cells in uremic patients are hyporeactive to inflammatory challenge and this may be one reason why uremic patients are vulnerable to infections.