This study aimed to determine the incidence of hospital admissions due to adverse drug reactions (ADRs) and to identify the associated risk factors and describe the main features of ADRs. The period of study was 120 days. Patients who were admitted to the Respiratory, Oncology, Cardiology and Endocrinology Departments of Chinese People's Liberation Army, General Hospital, Beijing, (n =142 beds) because of ADRs were included in the study. Demographic data, clinical and drug-related variables, smoking history, alcohol abuse, and the number of drugs on admission were registered and analyzed. Suspected drugs and main features of ADRs were described. A total of 1001 patients were assessed and 36 (3.6%) were admitted to the four departments because of ADRs. Using the Naranjo criteria, 36 hospital admissions due to ADRs were classified into the categories of "possible" (n = 6), "probable" (n = 20), and "definite" (n = 10). Hypoglycemia, bone marrow depression, and leucopenia were the most frequent ADRs. Antidiabetics (7/36) and antineoplastics (21/36) were the main suspected drugs. Logistic regression analysis showed that a history of drug allergies (OR: 2.297, 95% CI: 1.080-4.887) and liver function (OR: 1.009, 95% CI: 1.003-1.015) were independent factors. A total of 3.6% of patients who were admitted to the four hospital departments had ADRs. A history of drug allergies was a protective factor and liver disfunction was a risk factor in patients with ADRs.