The thermal behaviour of a main-chain thermotropic co-polyester has been investigated by differential Scanning Calorimetry. Crystallization and melting have been studied through the effect of the annealing time and temperature on the transition temperatures and enthalpies. Two melting peaks are observed, the first one clearly developping on annealing. Hypotheses are suggested about the crystallization mechanism. The glass-transition (rate-dependent) appears broadened and does not show hysteresis on heating and cooling through the transition temperature.