Objective：To investigate the expression and significance of cylindromatosis（CYLD） in pathological scar tissues and fibrob－lasts. Methods：Seventy-two skin specimens were collected from clinical patients and were divided into normal skin group（20 samples），normal scar group（14 samples），Keloids group（25 samples） and hypertrophic scars group（13 samples）. Immunohistochemistry and Western blot were used to detect the protein expression of CYLD in each group and the results were compared. Keloids，hypertrophic scars and surrounding normal skin tissues（10 specimens of each group） were collected for primary fibroblasts culture with tissue adherent method. Expressions of CYLD protein in the three kinds of fibroblasts were detected by Western blot. Results：The results of immunohistochemistry showed that the positive expressions of CYLD protein in group A and group B were significantly higher than those in group C and group D（F=213.832，P=0.000）. There were statistically significant differences in expression of CYLD protein be－tween group A and groups C，D（P=0.000） and between group B and groups C，D（P=0.000）. ②Results of Western blot showed that the expression of CYLD protein in normal skin tissues and normal scars tissues were higher than those of keloids and hypertrophic scars（F=424.685，P=0.000）. ③Expressions of CYLD protein in normal skin fibroblasts were also significantly higher than those of keloid fibroblasts and hypertrophic scars fibroblasts（F=90.306，P=0.000）. Conclusion：Expression of CYLD protein in pathological scar fi－broblasts is lower than that of normal skin，indicating that the low expression of CYLD may play an important role in the formation of pathological scar.