The effect of accelerated aging by immersion in boiling water on the tensile behavior of a hybrid ramie-cotton fabric polyester composite was evaluated. Under these conditions, fast water absorption by the lignocellulosic fibers took place, causing a sharp reduction in the tensile strength of the composite during the first 5 h of immersion. A decrease in Young's modulus and an increase in the deformation at break were observed at longer immersion times. It was shown that resin embrittlement occurred under the aging conditions used in this work, which was attributed to the leaching out of low molecular weight substances. Therefore, the plasticizing effect observed with the composites was attributed to the presence of the lignocellulosic fibers. The water absorption kinetics were satisfactorily modeled using the Fickian model.