A pilot study of bioindicators of environmental health was performed in a non-industrial region of Poland in April 2008. Twenty wild-caught northern pike Esox lucius Linnaeus, 1758 were used. Established biomarkers of environmental stress were studied in these fish, including condition factor, macroscopic lesions, morphometry of hepatic melanomacrophage cells, follicular atresia, and histopathology of liver and gonads. Body weight, total body length, and gender were recorded; livers, gonads, and organs with macroscopic lesions were collected for histopathology. H&E-stained paraffin-embedded sections were studied by light microscopy. All fish appeared in good health and had no macroscopic lesions except for two fish with gut trematodes. Microscopic lesions were minimal and included peribiliary fibrosis and cholangitis, focal hepatic necrosis and vasculitis, biliary myxozoanosis, intestinal metazoan parasites, and post-spawning peritonitis. Very low levels of hepatic MMC and ovarian follicular atresia were found. The data constitute the first report of biomarkers of environmental stress in northern pike from northeastern Poland and can be used as a reference for future monitoring of fish health and aquatic pollution in this region.