To investigate the current status of elderly dementia patients with physical illnesses and identify optimal care strategies for this growing population. This retrospective study included elderly dementia patients who (i) received in-patient treatment for a physical comorbidity at the dementia ward of the Juntendo Tokyo Koto Geriatric Medical Center, and (ii) who were discharged from April 2009 to March 2011. The study population was 390 patients (144 males, 246 females), with a mean [±SD] age of 80.5 [±8.1] years. Two hundred thirteen of the patients had Alzheimer's disease; the remaining 177 had other types of dementia. The comorbidities necessitating admission were: malignant neoplasms (n=65), respiratory conditions (n=57), genitourinary conditions (n=50), trauma or fracture (n=41), and other (n=177). Among the 239 subjects who were hospitalized from their homes and who were discharged alive, 157 (65.7%) returned to their homes. The hospital stays of patients who were discharged were significantly shorter (P<0.000) and their N-ADL scores were significantly better at admission (P<0.013) and at discharge (P<0.000). The proportion of subjects who were capable of oral ingestion was significantly higher among the patients who were discharged to their homes (P<0.025). The subjects who lived in their homes alone at the time of hospitalization were significantly less likely to be discharged to their homes (P<0.018). Elderly dementia patients should ideally return home after hospitalization for comorbid illnesses. This was facilitated by minimizing their hospital stay. During in-patient treatment, efforts should be made to maintain their N-ADL levels and support their oral intake.