The study had been carried out between July 2009 and June 2010 on the food chainrncomponents of Lake Ziway. Bioaccumilation and biotransference of heavy metals andrnorganochlorine pesticides were measured and determined in tilapia (Oreochromisrnniloticus) and Abyssinian ground hornbill (Bucorvus abyssinicus) to evaluate ecologicalrnhazard levels. Heavy metals were determined using flame atomic absorption spectroscopyrnafter digestion of the samples under reflux on kjeldhal hot plate apparatus using HNO3,rnHCLO4 and H2O2. Sample extraction for organochlorine pesticides analysis was carriedrnout in a Soxhlet apparatus using mixtures of n-hexane and acetone (4:1) and clean up wasrncarried out using SPE Cartridge (C-18 column). Gas chromatograph equipped with massspectrometerrn(GC-MS) was used for the detection and quantification of the organochlorinernpesticides. Heavy metals; Cu, Zn, Cd and Pb were investigated with mean concentrationsrnof 1.13 mg/kg, 27.13 mg/kg, 0.35 mg/kg and 0.28 mg/kg in tilapia and 8.91 mg/kg, 139.08rnmg/kg, 0.225 mg/kg and 0.286 mg/kg in Abyssinian ground hornbill muscle tissuernsamples. The detected organochlorine pesticides were dieldrin, DDT and the metabolitesrnof DDT (DDD and DDE). DDT and DDD are below the detection limit in tilapia andrndetected with mean concentration of 0.19ng/g and 0.14ng/g in Abyssinian ground hornbillrnsamples. Dieldrin and DDE were detected in mean concentrations, 4ng/g and 0.45ng/g inrntilapia and 11.8ng/g and 12.61ng/g in Abyssinian ground hornbill samples. Zn and Curnindicated biotransference up the food chain with 5 folds and 7.9 folds, respectively whilernCd and Pb showed lower concentration in the predator bird. DDE and dieldrin wererndetected in the bird sample with 28 and 3 folds higher than the amount detected in the fishrnmuscle tissue, respectively. From the detected heavy metals and organochlorine pesticidesrnZn, Cu, dieldrin, DDT and its metabolites indicated positive biotransference through thernfood chain. The concentrations of the detected heavy metals and organochlorine pesticidesrnwere compared with threshold limits set by international organizations and the levels arernwithin the accepted limits.rnKey words; Organochlorine, Bioaccumulation, Contaminant, Biotransference