SUMMARYFollowing the rapid intravenous injection of corticosteroids (cortisol, prednisolone, betamethasone and betamethasone‐17‐valerate), the blood levels of each were estimated and the results analysed in a two‐compartment open model. The kinetic analysis revealed differences in distribution and elimination which could have important therapeuticimplications. A theory is presented for the marked differences seen, and the therapeutic importance of these is disc