The melt behaviour of poly(p-dioxanone) (PPD) has been studied by differential scanning calorimetry (DSC). Crystallinity and morphology were evaluated by modulated differential scanning calorimetry (MDSC) and polarizing optical microscopy. The melting curves showed two melting endotherms, a higher melting (HM) peak at a constant temperature of 105 degreesC and a lower melting (LM) peak at temperatures depending on the crystallization temperature T-c. The corresponding peak temperature increased linearly with T-c, yielding an extrapolated value for the equilibrium melting temperature, T(m)degrees, of 114 degreesC. The occurrence of HM peak is a result of recrystallization. The optical micrographs showed a spherulitic morphology, with regular concentric rings, which might be caused by a periodical twisting of the lamellae during crystallization.