As part of the radon and helium monitoring program for earthquake prediction studies in Southern California, concentrations of radium-226 in groundwaters have been measured along the major fault zones including the Palmdale area. Radium was measured in order to obtain information on its spatial variation as well as baseline levels. Several measurements were made at selected sites to examine their temporal variations. Radium concentrations are used to define the portion of radium supported radon in the observed groundwater radon. Radium levels vary spatially by 4 orders of magnitude (0.015 to 146 dpm/kg), but temporally by a factor of 2 or less. Similar spatial and temporal variations are observed in groundwater radon (60 to 46,700 dpm/kg). The radon/radium activity ratio ranges from 10 to 105. These values indicate that radon is in large excess over radium in groundwaters because of radon diffusion from the ambient rocks. The spatial variations of radon, radium and the activity ratio are probably due to different chemical and physical properties of the rocks through which groundwaters flow. The dependence of groundwater radium concentrations on the water temperature and conductivity is explored. It appears that radium increases in general with conductivity but not necessarily with temperature. Radium is probably leached more readily into the groundwater when the water is more conductive with more dissolved chemical constituents.