The pathogenesis of INS is related to the disorder of cellular immunity. Using the in situ hybridization of biotin-labeled probe and streptavidin -alkaline phosphatase conjugate detection system, we quantitatively analysed by true colour medical image analysis system the expression of IL-1 beta, IL-1ra mRNA of peripheral blood mononuclear cells (PBMC) from 4 cases of idiopathic nephrotic syndrome. IL-1 beta IL-1ra mRNA expression of PBMC in INS were significantly lower than those of the normal control (107.63 +/- 20.80 vs 195.56 +/- 31.14; 144.45 +/- 11.42 vs 370.38 +/- 100.48, respectively, P < 0.05). The expression of IL-1 beta mRNA was significantly lower than the IL-1ra mRNA expression of PBMC in INS (107.63 +/- 20.80 vs 144.45 +/- 11.42, P < 0.05). There existed dysregulation of IL-1 beta, IL-1ra mRNA expression in INS. The advantages of biotin-labelled probe in situ hybridization were also discussed.