It has been shown [1, 2] that a wide class of 3D motions of in- compressible viscous fluid in Cartesian coordinates can be de- scribed by only one scalar function dubbed the quasi-potential. This class of fluid flows is characterized by three-component velocity field having two-component vorticity field; both these fields can depend of all three spatial variables and time, in gen- eral. Governing equations for the quasi-potential have been de- rived and simple illustrative examples of 3D flows have been presented. In this paper the concept of quasi-potential is fur- ther developed for fluid flows in cylindrical coordinates. It is shown that the introduction of a quasi-potential in curvilinear coordinates is non-trivial and may be a subject of additional restrictions. In the cases when it is possible, we construct il- lustrative examples which can be of interest for some practical applications.