In this study, the levels of some heavy metals in the muscle tissue of spiny eels (Mastacembelus mastacembelus) living in Keban Dam Lake were investigated. For this purpose, the levels of copper (Cu), iron (Fe), zinc (Zn), chromium (Cr), cadmium (Cd) and lead (Pb) were investigated in the muscle tissue of spiny eels and in their surrounding water. The Pb was not determined due to being below of Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) detection limit. The concentrations of heavy metals in the water samples were found to vary by season. It was found that the levels of heavy metals detected in muscle of M. mastacembelus varied depending on the body weight, body length and sex of the fish. In conclusion, it was determined that the levels of heavy metals detected in muscle tissue of M. mastacembelus were below the acceptable values suggested by Environmental Protection Agency (EPA), Food and Agriculture Organization (FAO) and Turkish Food Codex (TGK).