Residents of a condominium building in Hoboken, New Jersey, were exposed to mercury contamination in indoor air. Elevated levels of mercury were detected in urine samples provided by the residents, and 69% of the urine mercury levels were 20 microg/l or greater. Urine mercury levels were correlated positively with the duration of residency in the building and with the time (i.e., h/d) residents spent in the building. Environmental and biomonitoring data indicated that the residents were being exposed to mercury levels that were cause for health concern. Local health authorities, therefore, declared the building to be unfit for habitation and ordered that the premises be vacated. Health officials monitored the personal belongings of residents for mercury contamination before the items were removed from the building. The residents were offered medical evaluations and support services as part of the relocation effort.