Objective To investigate the characteristics and patterns of causes of death in the hospitalized senile adults in order to provide the evidence and guidance for the clinical treatment and management of patients over 80 years old. Methods A total of 1684 death records of the hospitalized patients aged 65 years or older admitted in our cardiological and geriatric departments from January 2005 to June 2014 were collected from the digital medical records system. They were divided into the ≥80-year-old group (n=997) and the <80-year-old group (n=687), and further divided into different gender subgroups. They were also divided into the patients from the cardiological department (n=820) and those from the geriatric department (n=864), and further assigned into different aged groups. Results The lengths of hospital stay were significantly longer in the males than the females from the ≥80-year-old group, so were in the <80-year-old group, with significant differences between the 2 genders (P<0.001). The mortality due to respiratory tract infection was obviously higher, but that due to cardiocerebral vascular diseases was remarkably lower in the males over 80 years old than those younger. Similar results were observed in the female patients. There were more ≥80-year-old patients died from respiratory tract infection and malignant tumor, but less patients died from cardiocerebral vascular diseases among those from the geriatric department than those from cardiological department. For the patients younger than 80 years old, those from the geriatricdepartment had higher mortality due to respiratory tract infection and malignant tumor, but lower death rate of cardiocerebral vascular diseases than those from the cardiological department (P<0.05). The ≥80-year-old male patients had higher mortality of respiratory tract infection, but lower mortality of cardiocerebral vascular diseases than the same-aged female patients. Among the patients from the cardiological department, those aged 80 or older had higher death rate of respiratory tract infection but lower rate of cardiocerebral vascular diseases than those younger (P<0.05). For the geriatric patients, the aged 80 or older had higher mortality of respiratory tract infection, but lower rate of malignant tumor than those younger (P<0.05). Conclusion Respiratory tract infection threatens the over 80-year-old patients, especially for the males. But the threat from cardiocerebral diseases is decreased comparatively.