Objective To investigate the cognition of depression and anxiety and recognition of physical and mental illness, and analyze their correlation in hospitalized elderly patients with chronic diseases. Methods A cross-sectional study was performed. A total of 206 hospitalized elderly patients with chronic diseases from a hospital were investigated using mini mental state examination (MMSE), Hamilton depression rating scale (HAMD), self rating anxiety scale (SAS) and elderly patients with chronic diseases questionnaire. Results The total scores in cognition of depression and anxiety were (5.95±3.05) and (4.92±3.20). The correct recognition rate of chronic disease was (97±8)%, and the correct recognition rate of mental illness was (47±29)%. The recognition of mental illness was positively correlated with the total cognition score of depression and three dimensions of thinking, spirit and mood (P 0.05). There was no significant correlation between recognition of mental illness and physical dimension of anxiety (P>0.05). Conclusions The cognitive level and cognition of depression and anxiety are low in elderly patients with chronic diseases. They tend to recognize the mental illness as chronic physical disease. Therefore, nurses should make depression and anxiety evaluation as routine assessment for the elderly patients with chronic diseases. Early identification of mental illness can avoid the delay of psychological intervention and acquire the best time of treatment. Key words: Chronic diseases; Depression; Anxiety; Cognition; Correlation