An analytical solution was obtained to evaluate the effect of friction on flow distribution in both dividing and combining flow manifolds. The governing equation follows the derivation given by Bajura (1971). A constant cross-sectional area of the manifold header and a constant friction factor along the manifold were assumed in order to obtain the analytical solution, expressed in terms of the lateral flow distribution as a function of two performance parameters, α (the friction parameter) and β (momentum loss parameter). Numerical results show that friction always increases flow imbalance in the combining flow configuration, but it may either increase or decrease flow imbalance in the dividing flow configuration, depending on the ratio of the lateral area to the cross-sectional area of the manifold.