Dermatophytosis is a common contagious disease caused by fungi known as dermatophytes. Aim of study: This study was conducted to know the effects of CARD9 genes with severe dermatophytes infections. Methodology: The study was carried out in the period beginning of December 2022 to end of June 2023.This study has been done at the Al-Hilla Teaching Hospital, Dermatology Unit, Babylon Government; ages range between 1 to ≥ 50 years in male and female. During the study a total 90 clinical specimens (Skin scraping and 5ml of blood) were obtained from all participants (50 dermatophytosis cases and 50 controls). Blood samples (whole blood ) introduced for RNA extraction for calculation of gene expression of CARD9 by RT-PCR. Results: The results for gene expression of CARD9 by RT-PCR revealed that the ΔCt mean of Card 9 mRNA in blood samples of patients group was (10.99) compared to the corresponding ΔCt mean in control group (8.79), significant increasing was observed in ΔCt mean of patient groups compared to the corresponding ΔCt means in control group. The relative expression (2-∆∆Ct) of Card 9 mRNA was decreased in patient group, significant difference was observed in means of (2 ̄ΔΔCt) (expression folds) within groups. When the dermatophyte patients were distributed patient group, Asthenozoospermia (AS), Oligoasthenozoospermia (OAS). The t mean of CARD 9 in blood samples of patient groups were [p(0.217)] compared to the corresponding t mean in control group (1.0000),significant p=0.001 decreasing was observed in t mean of CARD9 gene. Conclusion: Decreased expression level of CARD9 gene in blood samples of dematophyrosis patients groups compared to control group.