Microcrystalline cellulose (MCC) was prepared by hydrolyzing waste cotton fabric with 2.5 N hydrochloric acid at 100 degrees C for 30 min. The structure, morphology, particle size, and thermal property of the prepared MCC were characterized by X-ray diffraction, scanning electron microscope, laser light scattering particle size analyzer, and thermogravimetric analyzer, respectively. The X-ray diffraction pattern showed that the obtained MCC has typical crystal lattice of cellulose I. The fibrous-shaped particle of MCC possessed an average particle size of approximately 40 mm and thermal degradation temperature of 350 degrees C. The produced MCC was blended with concentrated natural rubber (NR) latex at the amounts of 10, 20, and 30 parts per hundred of dry rubber. The blended latex was cast into a sheet on a glass mold, allowed to air dry, and subsequently cured at 100 degrees C for 3 h. After curing, samples were tested for their tensile properties, water absorption, morphology, and biodegradability. It was found that the tensile properties of NR decreased when incorporated with MCC. However, the 100 NR/20 MCC sample showed the highest tensile strength and percent elongation at break. Water absorption and biodegradability of the sample were enhanced as the amount of MCC was increased. The results indicated that MCC caused important effects in promoting the biodegradability of NR.