The dielectric behaviour of poly(3-hydroxybutyrate) (PHB) has been investigated for the glass (alpha) relaxation in the temperature and frequency ranges of -60 to 100 degrees C and 10(3)-10(5) Hz, respectively. Also, the crystallization kinetics of PHB has been studied dielectrically as a function of heating rate, time and temperature. Crystallinity has a marked influence on the glass relaxation characteristics owing to the relative constraint imposed on the amorphous phase by the crystallites. Furthermore, the results obtained showed that : (1) the optimum crystallization temperature is about 25 degrees C; (2) the time at which crystallization starts is a function of the working temperatures and apparently is reduced to just a few minutes at 40 degrees C; and (3) the crystallization process is completed within a period of less than 1 h in the temperature range 20-40 degrees C. The bulk crystallization phenomena could be also described by the Avrami equation with an exponent similar to 3.8.