The low protein content of natural rubber was prepared in latex stage by the novel procedure to remove all proteins from natural rubber with either urea or acetic acid or ammonium sulfate and a polar organic solvent as a cacatyst in the presence of sodium dodecyl sulfonate (SDS) surfactant. The condition for the removal of proteins was investigated in terms of concentration of the solvents, and repeating times for washing latex with centrifuge. Acetone and anionic surfactant were found to be effective for the removal of the proteins. Remaining proteins assessed by the amount of nitrogen in the sample was determined by Kjeldahl method. The results showed in the presence of acetone, wt% of nitrogen decreased from 0.02 wt% to 0.005 wt%, i.e. removal efficiency increased 4-fold compared to not using acetone. In addition, the study also found that when using various amount of acetone, different removal efficiencies were obtained. Optimal concentration of 0.25% by weight of acetone and nitrogen content in the sample was removed to 0.005 wt% after three centrifugation. The removal of proteins from natural rubber was confirmed via Fourier Transform Infrared (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy.