The aim of this study was to compare environmental quality in two sites of the river in Western Ukraine, rural (R) and industrial (I) during three seasons via a set of biochemical markers in carp Cyprinus carpio L. Upon comparing the values of the I-site with those of the R-site, we found that Mn- and Cu, Zn-superoxide dismutase (SOD) activities decreased and O(.) production increased; metallothionein (MT) and glutathione levels increased in most cases, and acetylcholinesterase (AChE) activity decreased in summer. This confirms our hypothesis about continuous environmental press at the I-site. The higher activity of catalase and lipid peroxidation (TBARS), as well as the increased levels of vitellogenin-like proteins at the R-site, compare to the I-site in spring reflects the permitting effect of agricultural discharges. According to the results of PCA, the most sensitive biomarkers of pollution are MT, TBARS, and AChE in liver.