Decorin is a member of small leucine-rich repeat proteoglycans. It is ubiquitously expressed, primarily in the skin. It participates in extracellular matrix assembly. It plays a role in cell adhesion and migration processes directly and indirectly via interactions with membrane receptors. Delayed-type hypersensitivity (DTH) response in mice is widely used as a model of allergic contact dermatitis, allowing the study of cell-mediated immune response in vivo. We demonstrated that decorin modulates oxazolone-induced DTH reactions in mice. These findings were associated with an increased percentage of circulating decorin-deficient neutrophils.Decorin-deficient polymorphonuclear cells (PMNs) display an increased adhesion to endothelial cells in vitro compared to the wild-type. This is consistent with increase adhesion of Decorin-deficient leukocytes to the blood vessel wall in our DTH model in vivo. Collectively, absence of decorin exerts a protective effect on oxazolone-induced contact hypersensitivity reactions. This may lead to the development of new strategies in the treatment of contact dermatitis