Polybrominated biphenyls (PBBs) are a class of new type organic pollutants. They have been widely used as flame retardants to reduce the fire risk on plastics, carpets, electronic equipment, textiles and building materials around the world. With a gas chromatographic retention time technique, vapor pressures (p) of six polybrominated biphenyls (PBB15, PBB26, PBB31, PBB49, PBB103 and PBB153) were determined as a function of temperature with dichlorodiphenyl trichloroethane (DDT) acting as a reference substance. Vapor pressures at 298.15 K ranged from 0.01 Pa for dibrominated biphenyl to 10(-6) Pa for hexabrominated biphenyl. According to these vapor pressures at different temperatures, Antoine parameters (A, B, C) of six PBBs were regressed with the least square method. The correlations between vapor pressure and temperature for six PBBs were obtained. In addition, the correlations between vapor pressures and molecular connectivity indexes have been studied with correlation coefficients greater than 0.99 and standard errors less than 0.08. The vapor pressures of PBBs were also estimated by their molecular connectivity indexes.