Abstract During irradiation of natural rubber (NR) latex for vulcanization, the latex proteins undergo disintegration which leaves a high soluble protein content in latex products. In order to follow up the effects of radiation on NR proteins, field latex was irradiated with γ-rays and the soluble protein concentration in the rubber phase and serum phase were analyzed. It was found that the water solubility of proteins in the latex increases with increasing dose. The soluble protein content in the cream phase (rubber) decreased where as that in the serum phase increased with radiation dose. SDS-PAGE analysis revealed that the 27 kD protein together with 14 kD appear in the radiation vulcanized latex up to a radiation dose of 160 kGy and at 320 kGy they disappear due to the disintegration by radiation. A new process for the preparation of protein free latex has been developed. In the new process the radiation-prevulcanized, centrifuged latex is subjected to dilution and then centrifuged. In the case of field latex, it is irradiated first and then centrifuged after dilution. The new process results in prevulcanized latex almost free from soluble proteins. Tensile strength of samples produced by the new process is comparable to that from the conventional radiation process.