The flow field design of low pressure steam turbines equipped with bowed and/or highly twisted blades require a fully three dimensional (F3D) flow field computer code. A modified Denton`s F3D code can be chosen as an analysis or a design tool to calculate flow field for this purpose. The original Denton`s code includes several loss models. These simplified models are not accurate enough to predict the LP turbine efficiencies. The code has been modified to incorporate a loss model, which has been correlated with cascade and turbine tests. A steam routine was also included in the modified code for the steam turbine application. The flow field predicted by this modified code shows good agreement with the model turbine test results.