Polylactide is one of the most widely used biodegradable thermoplastic nowadays. However, some of poor properties of PLA include its brittleness, low impact strength and low thermal stability. The poor thermal stability led to degradation of PLA and thus to lower tensile and impact properties. One of the methods to improve its brittleness is to blend with natural rubber and, in some processing techniques, compatibilizers were also applied to expedite dispersion of natural rubber into the PLA matrices. However, these additives might have caused more severe degradation to PLA during processing and/or slow down the crystallization rate. Thus, this research investigates the effect of these additives on thermal stability and crystallization properties of the blends. In addition, the effectiveness of two different anti-degradation agents including polycarbodiimide and ANOX® in delaying degradation of the blend was also studied. The effects of all these additional chemicals on thermal stability were probed by using the rheological technique, whereas their effects on crystallization were carried out by using DSC. It was found that the addition of NR showed signs of increased degradation rate compared to that of neat PLA, where the absence of oxygen did not help reducing the degradation of PLA/NR blend. The compatilizing agent has caused significant drops in the complex viscosity with respect to neat PLA due to its lubricating effect, but did not change the degradation rate of PLA. Moreover, the polycarbodiimide provided better thermal stability to the blends than ANOX®. Unfortunately, the polycarbodiimide has interfered with the crystallization of the blend. It was also found that NR and some compatibilizers have caused a delay in crystallization of PLA.