Aim We have recently developed and validated a screening test for comprehensive geriatric assessment (CGA). We investigated the prevalence of geriatric problems in elderly inpatients using CGA, and determined the relationship between geriatric problems and cognitive decline. Methods We enrolled consecutive elderly inpatients aged >65 years who were admitted to all of the hospital departments at Tokyo Medical University Hospital, Tokyo, Japan, between July and December 2013. We investigated the prevalence of specific geriatric problems or situations in elderly inpatients using a screening test for CGA named “Dr. SUPERMAN.” We examined 3969 elderly inpatients (2211 men and 1758 women; mean age 75.5 ± 6.7 years) using CGA. Inpatients were divided into three groups by age, namely, 65–74 years, 75–84 years and ≥85 years. Inpatients were divided into the two groups of “internal medicine” and “other departments.” Results Geriatric problems were more frequently found in patients who were aged ≥85 years and admitted to “internal medicine” departments. Furthermore, multiple regression analysis found cognitive decline significantly correlated with ADL decline, age, poor medication adherence, upper and lower extremity function disorder, visual/auditory disorder, and urinary disorder. In particular, cognitive decline strongly correlated with a decline in activities of daily living. Conclusions CGA should be considered for the treatment of elderly inpatients, particularly those with cognitive decline and admitted to “internal medicine” departments. Geriatr Gerontol Int 2017; 17: 1252–1256.