The role of the GST genes in allergic diseases such as asthma and nasal polyps has been investigated before.10, 26Glutathione S-transferase polymorphism in nasal polyps has been investigated in previous studies, and only GSTT1 levels have been found to be associated with polyp pathogenesis.26Both studies were about genetic analysis and tissue investigation, but the role of GST at the tissue level was not investigated.11, 26In our study, we investigated the level of GST and CYP expressions in ACP tissue. The gene discussed is PPIG; the disease is nasal cavity polyp.