Referring to previous work carried out in organic solvents, a study of the action of nucleophilic reagents on epoxidized units of 1,4-epoxidized polyisoprene (synthetic polyisoprene or natural rubber) was performed in latex medium. Among the considered reagents, dialkylphosphate and ammonium diethyldithiophosphate demonstrated the ability to add under these reaction conditions on epoxidized units according to a SN2 substitution with an oxirane ring-opening mechanism. A systematic study was performed with dibutylphosphate that was shown to be very reactive. Grafting of phosphorated groups along polyisoprene chains was carried out via reaction of the acidic function (P-OH) of the phosphate with oxirane rings previously created on a 1,4-polyisoprene backbone. The prominent role of latex pH on the reaction was shown. (C) 2004 Wiley Periodicals, Inc.