The purpose of this study was to investigate the frequency of inpatient falls and to evaluate the risk factors of drugs in an academic hospital. The study population consisted of inpatients at Ehime University Hospital in Japan and the study was conducted from April 1st to October 31st, 2006. Children and teenagers (<18 years old) were excluded. Inpatient falls were registered regularly with incident reports submitted by nurses and other hospital employees discovering the fall. Logistic regression techniques were used to estimate the odds ratios (OR) of the association of falls and drug use. Of the 4084 adult patients, 65 (1.6%) fell. An OR (unadjusted) for risk of falling were observed for various drug classes; hypnotics (OR 2.12; 95% CI, 1.25 to 3.52), anxiolytic (OR 3.35; 95% CI, 1.83 to 5.82), anti-Parkinson's (OR 5.79; 95% CI, 1.71 to 14.80), narcotics (OR 3.08; 95% CI, 1.06 to 7.11), hypotensives, diuretics (OR 2.39; 95% CI, 1.42 to 3.95). A multivariate logistic regression analysis showed that inpatient falls were significantly associated with patients older than 70 years (OR, 2.25; 95% CI, 1.35 to 3.77), with patients taking anxiolytic drugs (OR 2.36; 95% CI, 1.24 to 4.25), and with patients taking anti-Parkinson's medication (OR 5.04; 95% CI, 1.44 to 13.43). In conclusion, this study provides information regarding the relationship between fall-related accidents and drugs. Therefore, pharmacists should provide appropriate drug information related to the risk of falling to both patients and medical staff members.