The variations in concentrations of stress-indicator blood parameters, such as serum glucose, aspartate, alkaline, lactate, cortisol, sodium, chlorine, calcium and magnesium, in two species of cyprinids (Squalius cephalus and Capoeta banarescui) exposed to the point pollutant sources (trash dump area and sugar factory) in Upper Yesilirmak River, Turkey were determined. Responses of blood parameters to environmental parameters, such as temperature, dissolved oxygen, conductivity, turbidity, nitrite, nitrate, ammonium and ortho-phosphate, were also evaluated to identify the most important environmental parameters that could cause stress to the fish. Water and fish samples were collected at three stations (Turhal, Tasliciftlik and Gumenek - control station) located in the Upper Yesiirmak River section in the city of Tokat, during winter 2009 and summer 2010. The ammonia and orthophosphate concentrations in Tasliciftlik station, where trash dumping area is located, were significantly higher (2.70 mg/L NH(3)-N, 4.14 mg/L PO(4)(-3)) than the control station, Gumenek (0.31 mg/L NH(3)-N, 0.11 mg/L PO(4)(-3)). In parallel to this finding of higher ammonia and ortho-phosphate concentrations in Tasliciftlik, concentrations of stress-indicator blood parameters, such as cortisol, alanine, aspartate, lactate (76.36 ug/dl cortisol, 1082 U/L alanine, 1143 U/L aspartate, 9564 U/L lactate) and magnesium (16 mg/L) were also significantly higher but concentration of sodium was lower than at the other stations, which suggested that fish inhabiting in trash dump area were under stress due to not heavy metals, which were higher in the station near the sugar factory, but more likely ammonia and ortho-phosphate or other substances leaking to the river from the trash dump area.