The heat capacity C(p) of solid mixtures of silybin and poly(vinylpyrrolidone) (PVP) K30 was measured by differential scanning calorimetry (DSC). The IUPAC name for PVP is 1-ethenylpyrrolidin-2-one, and that for silybin is 3,5,7-trihydroxy-2-[3-(4-hydroxy-3-methoxyphenyl)-2-hydroxymethyl-2,3-dihydrobenzo-[1,4]dioxin-6-yl]-chroman-4-one. By analyzing the curves of (dC(p)/dT) against temperature T. some apparent points, a maxima point and a minima point, to characterize the C(p) curve were obtained. The maxima point in the region w(1) <0.4 is a character of amorphous solid state of PVP, where w(1) is the mass fraction of silybin. In this region, silybin is dispersed into the amorphous solid of PVP. The minima point in the region of w(1) >0.4 is a character of crystalline silybin. In this region, a mixture of crystalline silybin and an amorphous solid dispersion is observed. (C) 2011 Elsevier B.V. All rights reserved.