Inflammatory bowel diseases are considered to be related to dysregulation of pro- and anti-inflammatory cytokines in the intestinal wall. We investigated the levels of TNFalpha, IFNgamma, and IL-10 mRNA expression in intestinal tissues resected from the patients with Crohn disease (CD) (n=29), ulcerative colitis (UC) (n=8), and controls (n=8) using reverse transcription-polymerase chain reaction (RT-PCR). In addition, we examined the relationship between the expression of these cytokine mRNA and their clinical conditions using CD activity index (CDAI) and Nutritional Surgical Risk Index (NSRI). Compared with controls, tissues in CD showed high levels of TNFalpha and IFNgamma mRNA expression both in inflamed and non-inflamed tissues, and showed high levels of IL-10 mRNA expression in inflamed tissues. In UC, high levels of IL-10 mRNA expression were detected both in inflamed and non-inflamed UC tissues, while those of TNFalpha and IFNgamma were not. In 80% of CD tissues (n=23), levels of IL-10 and TNFalpha expression were interrelated. While the remaining tissues (n=6) showed low levels of IL-10 expression despite high levels of TNFalpha expression in inflamed CD tissues, and 4 of these 6 patients had high CDAI and low NSRI. Furthermore, in low nutritional CD patients (NSRI <40, n=13), the levels of IL-10 mRNA to inhibit pro-inflammatory cytokines were poorer than in good nutritional patients (NSRI >/=40, n=16). These findings suggest the overexpressions of TNFalpha and IFNgamma in CD, and less producibility of IL-10 against these cytokine might lead to development of severe CD.