An analytical investigation of the effects of an initial splitter plate boundary layer on the flow field associated with the slot injection of a gas in laminar flow is presented. The analysis is based on the method of collocation, using profiles generated by a modified Oseen approximation to the momentum equation, and the results are presented in terms of the effects on skin friction and heat transfer coefficients. It is shown that the initial boundary layer thickness can be an important parameter in describing the flow field.