We examine the differences in the net present values (NPVs) of North Sea oil projects obtained using the weighted average cost of capital and a modern asset pricing (MAP) method which involves the separate discounting of project cashflow components. NPV differences of more than $10 million were found for some oil projects. Thus, the choice of valuation method will affect the development decisions of oil companies and could influence tax policy. The results of the MAP method are very sensitive to the choice of parameter values for the stochastic process used to model oil prices. Further research is recommended before the MAP method is used as the sole valuation model.