Immune deficiency is one of the numerous physiological alterations associated with chronic renal failure. Recurrent bacterial infections, diminished vaccinal response or beta2-microglobuline amyloïdosis are some common features of clinically well known dysregulations of uraemic immune functions. During the last ten years, our knowledge concerning the molecular and cellular effectors involved in the immune response has considerably progressed. Recent data clearly demonstrated that despite their activated phenotype, the effector capacity of the immune cells are severely hampered. Of interest, those abnormalities are not corrected by haemodialysis which sometimes even accentuate them. However, the presence of uraemic toxins in the serum of chronic renal failure patients jeopardise the determination of the factors responsible for the alteration of immune response in those patients. Among those molecules, the soluble form of CD40 (sCD40), which seric levels are dramatically increased, seems to play a crucial role. A better understanding of the molecular and cellular actors involved in the immune disorders of uraemic patients should allows the emergence of new immuno-intervention strategies and improve haemodialysis traitement.