Protocatechuic acid (PCA), a phenolic compound of anthocyanins, was reported to possess various pharmacologic properties, including anti-oxidant, anti-inflammatory, anti-apoptosis, anti-diabetic and anti-tumor activities. However, the role of PCA in diabetic nephropathy remains elusive. The present study was conducted to evaluate the effects of PCA on extracellular matrix (ECM) accumulation in high glucose (HG)-induced human mesangial cells (MCs) and explore the possible mechanism. Our results demonstrated that PCA obviously inhibited HG-induced proliferation of MCs in a dose-dependent manner. In addition, PCA effectively reduced the protein expression levels of type IV collagen, laminin and fibronectin induced by HG, as well as decreased the levels of ROS and MDA in HG-stimulated MCs. Mechanistic studies showed that PCA efficiently down-regulated the phosphorylation level of p38 MAPK in HG-stimulated MCs. Taken together, our present study demonstrated that PCA protects MCs against HG damage might via inhibition of the p38 MAPK signaling pathway. Thus, PCA might be a beneficial agent for the prevention and treatment of diabetic nephropathy.