Abstract: Fingerlings tilapia fish (Oreochromis niloticus) were exposed in laboratory conditions to a range of Copper (Cu), Cadmium (Cd), Lead (Pb) and Zinc (Zn) concentrations separately and the mortality rate were registered after 24, 48, 72 and 96 h. Median Lethal Concentrations (LC50s) and Median Lethal Times (LT50s) values were calculated by static bioassays for 24, 48, 72 and 96 h with the 95% fiducial limits through Probit analysis. LC50 and LT50 increased with the decrease in mean exposure times and concentrations, respectively. The LC50s for 96 h for Cu, Cd, Zn and Pb were 1093, 3751, 16177 and 1494 μg L-1, respectively and the LT50s for maximum concentration used for Cu, Cd, Zn and Pb were 20.25, 11.48, 20.70 and 24.66 h, respectively. Metals bioconcentration in tilapia fish increases with exposure to increasing concentrations and Cu was the most toxic to tilapia fish, The toxicity ranking of the four heavy metals was Cu>Pb>Cd>Zn. Comparison of LC50 values for studied heavy metals for this species with those for other fishes reveals that tilapia fish (Oreochromis niloticus) is equally or less sensitive to heavy metals than most other tested fishes.