Nasal polyps are characteristic feature of human atopic allergic inflammation, but the pathogenesis is not clearly understood. Recently it is suggested that action of individual cytokines may play important roles in the pathophysiology of allegic disease in vitro. But the information regarding the pattern of cytokine expression in vivo in allergy has been seldom reported. This study was undertaken to find out difference between nasal polyps and normal nasal tissues in the pattern of gene expression of cytokines by reverse transcription-polymerase chain reaction(RT-PCR) and Southern blot. In nasal polyps compared with normal nasal tissues, there wee significant increment of IL-4 and IL-6 mRNA, which are known to be the products of Th2 cells. However, IL-2 and INF-r mRNA were not observed in both nasal polyps and normal nasal tissues. In nasal polyps, there were significant increases in mRNAs for TGF-β1 abd IL-3. These results suggest that the pathogenesis of nasal polyps is associated with the migration and activation of cells, which express TGF-β1 and IL-3 mRNAs as well as IL-4 and IL-6 mRNAs.