Dissolution rates (DR) of methylprednisolone polymorphs I and II were determined by the rotating disk method as a function of rate of rotation (RR). The results show that the DR-RR relationship differs from that normally expected in the case of diffusion-controlled dissolution from rotating disks. The experimental data confirm the observations by Hamlin, et al. (5), that differences in DR between methylprednisolone polymorphs diminish at higher agitation intensities and indicate that this is due to an intrinsic property of the drug and is not caused by particular apparatus or methodology. From DR-RR data on methylprednisolone I, it was possible to determine the approximate agitation intensities, in terms of rotating disk r.p.m., obtained with five commonly used dissolution methods. These values are shown to be in reasonable agreement with those calculated independently from aspirin and salicylic acid data.