The purpose of this study was to explore consequences of accelerated weathering on the behavior of polylactide/halloysite nanotube composites. Nanocomposites were compounded by melt mixing method via a twin-screw extruder while specimens for testing and analyses were shaped by injection molding. Behaviors of the specimens were compared before weathering and after exposure to UV irradiation and humidity steps according to Cycle-C of ISO 4892-3 standards for a total duration of 300h. IR studies revealed that photolysis and partly hydrolysis were the main degradation mechanisms leading to random main chain scission of the PLA macromolecular structure, which was reflected with drastic reductions both in the molecular weight of PLA and the mechanical properties of flexural strength and fracture toughness. On the other hand, no significant reductions were observed in the values of thermal degradation temperatures, storage modulus and flexural modulus of the specimens, which was due to the compensating effect of higher amounts of crystallinity formed during UV irradiation cycles at 70?.