An integral-type method for boundary layer prediction is proposed which can account for detached zones of limited extent. An extension of Kuhn s (1970) two-layer model is used for the turbulent viscosity model. In the internal zone, Kleinstein s (1967) expression for turbulent viscosity is used, while in the external zone, Clauser s (1973) model, modified by an intermittence factor, is adopted. The singularity at the point of detachment is eliminated by an interaction equation. Displacement thickness and friction velocity can be calculated from external flow data, while the flow field can be determined when either one of those quantities is given. Experimental points from two other sources fit well onto the curve calculated on the present model.