The accumulation of heavy metals (Cu, Fe, Zn and Mn) was measured by atomic absorption spectrophotometry in some organs of tench (Tinca tinca L., 1758) and tissues of its parasite collected from Beysehir Lake, and compared with the data from sediments and water. The Cu levels in L. intestinalis L., 1758 plerocercoids were 1.69 times, respectively, higher than those in fish gill. Zn level in L. intestinalis plerocercoids was 2.13 times higher than those in fish liver, was 5.53 times higher than that of the muscle and 3.33 times higher than that in the gill. Significant negative (for Mn) correlation was found between the quantity of heavy metals in water and tissues of L. intestinalis plerocercoids while there was significant negative (for Cu) correlation between the quantity the heavy metals in bottom sediment and tissues of L. intestinalis plerocercoids. This study supports the idea that cestodes aren't very useful to determine the heavy metal pollution in aquatic system when they are located in their intermediate host's body cavity.