A falling film with waves on a vertical circular tube has been analyzed using the integral approach. A theoretical model of free surface deflection has been developed. The nonlinear equation obtained in the present work is similar to the deflection equation of a wave on a flat plate, It becomes exactly the same as the wave equation on a flat plate in the case of an infinite radius. This study shows that the wave characteristics depend on the parameters such as wave number, dimensionless wave velocity, tube radius and Reynolds number. As the tube radius decreases, the intensity of the wavy processes increases. The velocity distribution of the falling film was investigated in the present work. The cylindrical model appears to be more appropriate over the Cartesian model when the film thickness to tube diameter ratio is large. Calculated values are in good agreement with other published data. (C) 2001 Published by Elsevier Science Ltd and IIR. All rights reserved.