The presence of manganese, copper, cadmium, lead, nickel, zinc, chromium and iron concentrations was examined between June 2000 and July 2000, in water and some Cyprinidae species (Barbus plebejus Bonaparte, 1839, Capoeta capoeta (Güldenstadt, 1773), Capoeta tinca (Heckel, 1843) and Leuciscus cephalus (Linnaeus, 1758)) from 11 sites within the Porsuk river in the northwest of Turkey suffering inputs from industrial and mining activities. Also, some parameters such as dissolved oxygen, temperature and pH of selected eleven stations in the Porsuk River were measured. The metal concentrations in the river water were found as in the range of 10-100 μg/L for Zn, 20-90 μg/L for Mn, 19-65 μg/L for Fe, 17.8-65.8 μg/L for Ni, 0.09-9.6 μg/L for Pb, 0.01-8.8 μg/L for Cd, 0.18-3.69 μg/L for Cu and 0.0067-0.025 μg/L for Cr. The metal concentrations found in the tissues of the four fish species varied considerably. The accumulation order of heavy metals in fish samples for liver was found to be Zn (Capoeta tinca) > Fe (Leuciscus cephalus) > Ni (C. tinca) > Mn (C. capoeta) > Cu (L. cephalus) > Cd (C. tinca) > Pb (C. capoeta) > Cr (C. capoeta).; for muscle Zn (L. cephalus) > Fe (L. cephalus) > Mn (C. tinca) > Ni (C. capoeta) > Cr (L. cephalus) > Pb (Barbus plebejus) > Cu (C. capoeta) > Cd (C. capoeta). The highest mean zinc concentrations (μg/gr wet weight) in liver and muscle were found to be 42.35-36.51 and 30-20.23 μg/g for Capoeta tinca and Leuciscus cephalus,respectively