The Berzheron method is used to determine the pressure generated in a well when casing is being lowered. The generated pressure is caused by flow of liquid displaced by the casing. Such liquid flow is transient and is described by unsteady-state type of equations, which are solved graphically. The graphical solution is rapid and relatively simple. Application of the solution to a specific example is shown. Conclusions from this study are: (1) collapse of casing can occur during the lowering operation, previous to time of landing; (2) both casing collapse and breakage of the check valve in the casing are caused by excessive lowering speed of large-diameter casing and the resulting high pressure; and (3) during the lowering operation, pressure varies in the well and such pressure variation can cause wall damage, water-gas appearance, and formation fracturing.