Purpose: To describe caries prevalence and oral-health-related behaviours in a sample of homeless adults from the city of Porto, Portugal. Materials and Methods: Subjects attending any of two temporary shelters or two institutions that provide meal programmes were consecutively invited (n = 196); 42 (21.4%) refused to participate. Trained interviewers applied a structured questionnaire to obtain sociodemographic, behavioural, health and oral health status data. An oral examination was conducted to evaluate the past and present history of caries (Decayed Missing Filled Teeth [DMFT] index) and the presence of oral lesions. Those classifi ed as houseless were considered for the present analysis (n = 141). The association between homelessness, sociodemographic and behavioural characteristics and oral health indexes was quantifi ed through crude β coeffi cients and β coeffi cients adjusted for age, gender, education, nationality and duration of homelessness, as well as the respective 95% confi dence intervals (CI). Results: The median age of the participants was 45 years, most were male (86.3%), reported having less than a 9thgrade education (80.1%) and were unemployed (82.1%). The median duration of homelessness was 24 months. The mean (SD) DMFT index, number of decayed, lost and fi lled teeth were 12.8 (7.9), 4.2 (4.4), 8.0 (7.6) and 0.6 (1.9), respectively. Older subjects and those homeless for longer periods presented higher DMFT index scores (β = 3.4, 95% CI: 0.0 to 6.8) and higher number of decayed teeth (β = 2.8, 95% CI: 0.4 to 5.2). Filled teeth were more frequent among the more educated (>9 vs ≤4 years: β = 1.6, 95% CI: 0.7 to 2.6). Conclusions: This population of homeless subjects showed poor oral health, particularly with respect to caries and missing teeth, resulting in high oral treatment needs. Keywords: caries, DMFT, homeless, oral health