1 Prednisolone plasma levels were measured in seven patients by a competitive protein binding method after administration of prednisolone (20 mg) by mouth as plain or enteric-coated tablets. 2 The mean peak plasma prednisolone concentration after the enteric-coated preparation, 199 ng ml-1, was significantly lower than after the plain tablet, 268 ng ml-1, and occurred later, at 4.69 h compared with 1.72 h. The bioavailability of the two preparations was similar. 3 It is concluded that, although the plasma concentration versus time profiles are different, the absorption of prednisolone from plain and enteric-coated preparations is equal.