[en] Very thin torispherical or ellipsoidal shells subjected to internal pressure are used in various industries and one possible mode of failure is circumferential buckling, involving a large number of waves, or lobes, around the circumference. It is, of course, essential to check that this failure mode does not occur in practice. For very thin shells, this means that non-linear large-deflection shell theory has to be used to calculate the elastic bucking pressures; such computations are often time-consuming and expensive, since a search for the minimum buckling pressure has to be made over many circumferential wave numbers. Incorrect buckling estimates may be obtained if the search is not made carefully or if a poor circumferential wave number is used as the initial choice. In the paper, the results of limited parametric survey on internal pressure buckling of constant-thickness shells are presented which, it is hoped, will aid designers of such structures. The minimum elastic buckling pressures were determined using the variational finite-difference program BOSOR 4 and they were cross-checked using the finite element program MIST 1. (Auth.)