An assessment of potential risk factors for substance use disorders was performed in 49 patients with major affective disorders in a general hospital acute care unit in Taiwan. The major depression patients were noted to have a higher prevalence of substance use disorder than bipolar disorder patients (p = 0.011). Those patients with substance use disorders were noted to be significantly male-predominated (p = 0.043), to have a later onset age of affective disorder (p = 0.009), and to have more visits to the emergency room in the recent one year (p = 0.009). The sedatives-hypnotics-anxiolytics was the most frequently used forms of drug abuse. The major depression patients had a significantly higher sedative-hypnotics-anxiolytics use disorder rate than the bipolar disorder patients (p = 0.001). All patients with alcohol use disorder were noted to have other substance use disorders as well. Fifty six percent of those patients with substance use disorder were polysubstance users. Eighty three percent of the male patients with substance use disorder had poly-substance use disorder.