In this experimental investigation of condensation heat transfer, the effects of film Reynolds number Re-F, Prandtl number Pr-F and interfacial shear stress tau (V) have been studied independently. For condensation without considerable interfacial shear stress tau (V), correlations from the literature are confirmed. In the case of increasing values of tau (V) a reduction in heat transfer coefficients is found for Re-F < 10 and an increase for 20 < Re-F < 670. With turbulent film the influence of the shear stress disappears. Apparently two opposite tendencies which balance each other are responsible for this: with low film Reynolds numbers, holding back the downward flow of liquid causes a deterioration of the heat transfer; with high Reynolds numbers, the intensification of waves and turbulent fluctuations causes an improvement. A correlation is suggested which predicts very well the influence of the vapour flow on the heat transfer as a function of tau (V) and Re-F. For the friction factor of the two-phase flow, correlations from the literature can be confirmed.