Human health would be at risk if water which is essential for every human activity is contaminated with carcinogenic substances including heavy metals, this present study evaluated potentially toxic metal concentration in some selected rivers in Ijebu-North of Nigeria to determine the concentration of heavy metals and evaluate the pollution index. Ten (10) rivers were randomly selected for the purpose of this study. Samples were collected using a labelled acid pre-cleaned polyethylene container so as avoid wall absorption, the samples were collected from different points at different locations along the course of the river. The samples were filtered, acidified with HNO 3 and analysed for heavy metals using Atomic Absorption Spectrometer (AAS). Concentrations of Pb, Ni, Cr and Cu in all the rivers were higher than the WHO limit. However Hg, Cd, Ag, Al, and Mn values are below the recommended values. The contamination factor (C_f) for the Pb varied from 2.18-4.04, Ni varied from 3.0-14.0, Hg was between 0.00-0.03333, Cd was between 0.16667-0.6667, Cr varied between 8.00-48.40, Cu varied between 4.00-12.00, Ag varied between 0.01-0.02, Se varied from 0.05-1.25, Al varied between 0.12-0.46 and Mn varied from 0.020-0.028, Cu values fall within the range of very severe pollution. The results from this study revealed that some rivers within the study area were polluted and recommended for treatment before they can be used domestically and for other purposes.