Today, suicide by self-poisoning of prescribed or non-prescribed drugs on purpose has been increasing and is a major cause of mortality. It is very important to treat promptly and properly for saving the lives from those suicides. There is neither an organization such as poison control center nor measurement in S. Korea, though. The object of this study was to evaluate information of frequently used substances for suicide attempt in S. Korea. Our results also can provide healthcare provider including pharmacists and doctors, etc and contribute to increasing health and welfare for Korean. From June $1^{st}$ 2006 to April $30^{th}$ 2012, we retrospectively studied patients visiting emergency room due to suicide attempt. We collected information of underlying disease, history of past medical condition and suicide attempt, ingredient and getting route of ingesting substances, emergency treatment, and outcome by reviewing electronic medical record. We also evaluated actual treatment of self-poisoning and made guide information about antidote medication for S. Korean healthcare provider. Among total 242 cases of suicidal attempts, cases ingesting substances including prescription, non-prescription drugs and agricultural chemicals were 86.4%. The most frequently used drugs for suicide attempt were sedatives-hypnotics (53.6%), followed by analgesics (16.7%) and antidepressants (12.4%). Analgesics including acetaminophen and aspirin were most in teenagers but sedatives-hypnotics including benzodiazepines, non-benzodiazepine (zolpidem) and antihistamine were most in other ages including elderly people. Most frequently used antidote was activated charcoal (62.7%) and specific antidotes for some substances (acetaminophen, aspirin, agricultural chemicals) were also treated properly, accompanying with medication for supportive care. In conclusion, the most used substances for suicide attempt were sedatives-hypnotics and treatments for self-poisoning in emergency room were appropriate based on existing references. Therefore, information of frequently used substances and antidote reflecting these results will be useful for South Korean healthcare provider.