OBJECTIVES--To survey the health status of the temporarily homeless population of North West Thames region and make comparisons with regional residents. DESIGN--Direct interview with standardised questionnaires. SETTING--Temporarily homeless people resident in hotels in the London boroughs in the North West Thames region and a random sample of regional residents. SUBJECTS--137 hotels thought to be providing accommodation to homeless people selected at random from a list of 295. 113 (82%) participated in the study, and 319 (61%) of 522 homeless people approached participated. The study was restricted to adults aged 16 and over selected at random. RESULTS--The homeless population was predominantly female (195/319; 61%), young (229 (72%) aged 16-34), and poor, 54% (172/319) receiving income support. 207 subjects (65%) had dependent children aged 16 and under. Rates of acute illness among homeless people (32 cases; 10%) were similar to those reported by regional residents. The prevalence of longstanding limiting illness (108 cases; 34%) was similar to that for regional residents, but the prevalence of mental morbidity was twice that for the region as a whole (145 cases (45%) v 1485 (18%)). Utilisation of general practitioner services, accident and emergency departments, and inpatient admission was much higher by the homeless population than by regional residents. General practitioner registration rates were above 90% for the homeless sample. CONCLUSIONS--Survey data provide empirical evidence about the nature and characteristics of the temporarily homeless population. The high service utilisation recorded may, in part, have resulted from the higher morbidity in this sample of homeless people. The concentration of homeless people into specific locations may suggest that additional funding should be provided to the district which provides care to this group. However, such funding should not necessarily be used for additional acute care but should be used to purchase appropriate services which meet the health needs of this very young, poor and vulnerable group.