Objective:To explore the relationship between comorbidity and oral health in the elderly.Methods:As a retrospective study, 852 patients hospitalized at the Department of Geriatrics, the First Affiliated Hospital of Chongqing Medical University between July 2017 and July 2018 were selected, including 380 male and 472 female patients, with 274 between 60 and 74 years old, 519 between 75 and 89 years old and 59 ≥90 years old.Patients' clinical data and records on the Chinese version of the Kayser-Jones Brief Oral Health Status Examination(BOHSE)were retrospectively collected.The cumulative illness rating scale(CIRS)and the Chinese version of the BOHSE scale were calculated.The distribution of oral health problems measured using indicators in the Chinese version of the BOHSE scale was compared between the comorbidity group and the non-comorbidity group.The relationship between the CIRS score and oral health was analyzed by multiple linear regression.Results:Of the 808 patients with comorbidities, each patient had(3.63±1.33), (4.26±1.64)and(5.14±1.90)diseases, respectively, in the 60-74, 75-89 and ≥90 age groups( F=35.555, P<0.01). The age groups' CIRS scores were(8.88±3.59), (11.67±4.32)and(13.64±4.42)( F=51.532, P<0.01). The incidence of oral problems in hospitalized elderly patients was 92.72 %(790/852). The average oral health BOHSE score was(4.58 ± 2.88). There was a significant difference in oral health condition among the 60-74, 75-89 and ≥90 age groups( F=19.370, P<0.05). There were also significant differences in gums between teeth and/or under artificial teeth, condition of natural teeth and condition of artificial teeth between hospitalized elderly patients with and without comorbidities(all P<0.05). CIRS scores of patients with comorbidities were correlated with scores of natural tooth condition and pairs of teeth in the chewing position(natural or artificial)( t values were 2.565 and 2.495, P<0.05 for both). Conclusions:The comorbidity rate of hospitalized elderly patients is high and their oral health problems are common.As the age increases, the number of comorbidities increases and oral health condition becomes worse.The natural tooth condition and pairs of teeth in the chewing position(natural or artificial)are related to the severity of comorbidities in the elderly.