BACKGROUND: To identify the determinants of health care use among homeless individuals. METHODS: Data were taken from the Hamburg survey of homeless individuals (n = 100 individuals in the here used model, mean age 44.8 years, SD 12.5) focusing on homeless individuals in Hamburg, Germany. The number of physician visits in the past 3 months and hospitalization in the preceding 12 months were used as outcome measures. Drawing on the Andersen model of health care use as a conceptual framework, predisposing characteristics, enabling resources and need factors as well as psychosocial variables were included as correlates. RESULTS: Negative binomial regressions showed that increased physician visits were associated with being female (IRR: 4.02 [95% CI: 1.60-10.11]), absence of chronic alcohol consume (IRR: 0.26 [95% CI: 0.12-0.57]) and lower health-related quality of life (IRR: 0.97 [95% CI: 0.96-0.98]). Furthermore, logistic regressions showed that the likelihood of hospitalization was positively associated with lower age (OR: 0.93 [95% CI: 0.89-0.98]), having health insurance (OR: 8.11 [2.11-30.80]) and lower health-related quality of life (OR: 0.97 [95% CI: 0.94-0.99]). CONCLUSIONS: Our study showed that predisposing characteristics (both age and sex), enabling resources (i.e., health insurance) and need factors in terms of health-related quality of life are main drivers of health care use among homeless individuals. This knowledge may assist in managing health care use.