Decline curve analysis using type-curve matching has become an established engineering tool to evaluate long-term production characteristics of oil and gas reservoirs producing under various drive mechanisms. Decline curve analysis is often used to satisfy various regulatory requirements, to establish reserves. and to evaluate the success or failure of operational changes made during a reservoir＇s producing life. In this study, a detailed investigation of production decline data from 78 Western Canadian Sedimentary Basin oil pools under waterflood conditions is presented. This study demonstrates that the majority of the waterflooded oil pools follow a hyperbolic decline with decline curve exponents ("b") less than 0.5. The decline exponent "b" does not exhibit any obvious functional relationship to the type of rock, oil density, geographical area, and/or geological formation. Nonetheless, such a study provides a basis for "b" values to be expected for Canadian oil reservoirs under waterflood conditions.