Background. Emergent, in-hospital, post-discharge care and outcomes for homeless trauma patients may be influenced by co-morbid illnesses and environmental conditions that impede self-care, rehabilitation, and home health services. Methods. Of 1.43 million hospitalizations in homeless or low socioeconomic status (SES) adult and elderly NYC residents from 2000 to 2002, 64,698 (4.6%) were for traumatic injury. Types/mechanisms of injury, co-morbidities, length of stay, and discharge status were examined for homeless (n=15,543) and low SES housed patients (n=49,156) aged 20 yrs and older using statewide hospital discharge data (SPARCS). Low SES was defined as uninsured, Medicaid, Medicare only, or Medicare plus Medicaid. Odds ratios were age and gender adjusted with 95% CI. Results. Compared to low SES housed, homeless trauma patients had increased odds of: diabetes (1.2, 1.1-1.3); circulatory disease (1.2, 1.2-1.3); mental illness (1.3, 1.2-1.3); alcohol dependency syndrome (1.3, 1.3-1.4); non-dependent drug abuse (1.4, 1.3-1.5), infection (1.4, 1.3-1.5), pedestrian injury (1.6, 1.4-1.7), cold exposure (2.5, 2.0-3.0), and late effects of injury (1.4, 1.2-1.6).  Homeless had lower motor vehicle occupancy injury (0.7, 0.6-0.8) than low SES housed patients. Conclusions.  In additional to surgical services, homeless need aggressive in-house medical and psychosocial screening for conditions that may delay or prevent recovery. Further study on the late effects of injury may improve post-trauma outcomes.