Sulfide samples collected by the deep submersible ALVIN from hydrothermal vents at 21¿N on the East Pacific Rise have extremely variable contents of uranium series nuclides. In samples we have analyzed, 210Pb and 210Po activities vary by more than an order of magnitude within the same vent. In two out of three samples measured 210Po activities are hgiher than the parent 210Pb activities. Consideration of 210Pb/Pb in particulate sulfide filtered from hot vent water indicates that the lead in these deposits has a basalt as opposed to a seawater origin. Comparison of 210Po and 210Pb contents of active and inactive vent particulates suggests that the cycle of buildup, cessation and decay by oxidation of these sulfide chimneys is measured in tens to a few hundreds of years.