Hospitals do not routinely collect data about homelessness. The objectives of the present study were to (1) describe rate of patient reports of homelessness among inpatients at a public hospital, (2) assess the agreement between patient report of housing status on a study questionnaire with clinical and administrative data about homelessness, and (3) assess changes in housing status during hospitalization. We conducted a cross-sectional survey of inpatients at an urban public hospital to assess housing status; we then examined subjects' medical charts to assess agreement with the questionnaire on housing status. Of inpatients, 25.6% were homeless at discharge. An additional 19.4% were marginally housed. One third of homeless persons had their housing status change during their hospitalization. Administrative data identified 25.6% and physicians' notes identified 22.5% as homeless. Clinical, administrative, and survey data did not agree. Homelessness and changes in housing status are common among inpatients at an urban public hospital. Poor agreement on who is homeless limits the usefulness of data.