AIM:The effects of cobalt,copper,cadmium and bariumions on the cysts of Entamoeba histolyt/ca (E,histolytica),an amebic dysentery agent,cultured in Robinson mediumwere investigated.METHODS:E.histolytica cysts and trophozoites isolatedfrom a patient with amebiasis were cultivated in the medium,incubated at 37℃ for a period of 4 days and 40×10~4/mlamebic cysts were then transferred to a fresh medium.Atthe second stage,0.05,0.1 and 0.2 mM of selected metalions were added to the medium,and the effects of theseions on parasitic reproduction compared with the controlgroup were observed.RESULTS:It was determined that the number of livingparasites in all the groups containing metal ions decreasedsignificantly starting from 30 minutes (P<0.01).CuCl_2 showedthe highest lethal effect on E.histolytica cysts,whereas thelowest lethal effect was observed with CoCl_2.It was alsoseen that the number of living cells was decreased as theion concentration and exposure time were increased,andthat there were no living parasites in the medium at the endof 24 h (P<0.01).CONCLUSION:It may be stated that the effect of ever-increasing contamination of the environment with metalwaste materials on parasites should be investigated further. AIM: The effects of cobalt, copper, cadmium and barium on the cysts of Entamoeba histolyt / ca (E, histolytica), an amebic dysentery agent, cultured in Robinson mediumwere investigated. METHODS: E. histolytica cysts and trophozoites isolatedfrom a patient with amebiasis were cultivated in the medium, incubated at 37 ° C for a period of 4 days and 40x10-4 / mlamebic cysts were then transferred to a fresh medium. At the second stage, 0.05, 0.1 and 0.2 mM of selected metals were added to the medium, and the effects of theseions on parasitic reproduction compared with the controlgroup were observed .RESULTS: It was determined that the number of livingparasites in all the groups containing metal ions decreased ignificantly starting from 30 minutes (P <0.01) .CuCl_2 showed the highest lethal effect on E. histolytica cysts, while the lowest lethal effect was observed with CoCl_2.It was alsoseen that the number of living cells was decreased as the concentration concentration and exposure time were increased, andthat there were no living parasites in the medium at the end of 24 h (P <0.01) .CONCLUSION: It may be stated that the effect of ever-increasing contamination of the environment with metalwaste materials on parasites should be further further.