The upper limit of the e+e- partial width of X(3872)

The e+e- decay partial width of the recently observed state, X(3872), is estimated using the ISR data collected at the center of mass energy 4.03 GeV in e+e- annihilation experiment by BES at BEPC. It is found that the product of the e+e- partial width and X(3872) --> pi+ pi- J/psi decay branching fraction is less than 10 eV at 90 % confidence level if the J(PC) of X(3872) is 1(–). Together with the potential models and other information, we conclude that X(3872) is very unlikely to be a vector state.