Accelerated ageing of curcubitea pepo seed oil was followed by simulation of UV (light) and ambiant oxygen actions held separately then simultaneously in order to know the effects of these parameters on this oil resistance to deterioraton. Nine withdrawals had undergone analyses by titrimetry supported by spectroscopic analyses notably MIR (Medium Infrared), DSC (Differential Scanning Calorimetry) and also a gas chromatography for the composition in FA. This study has showed that pumpkin seed oil displays a weak resistance to UV which results among other in a decrease of unsaponifiable compounds. Its oxidization takes place very quickly in the presence of ambiant oxygen. However the accumulated action of the two factors weakens to the highest degree pumpkin seed oil and this results in polymerization. It has also enabled us to show the link between the formation of recticulations in the oil matrix and variations at the level of the molecular structure of pumpkin seed oil.