Self-harm is a person's behavior who intentionally injures his body in various ways without any suicidal intent. Self-harm behavior can include slicing the skin with a razor or other sharp object, burning the body, hitting oneself, picking at scars, pulling hair, and consuming toxic substances. People with self-harm behavior are at high risk of committing suicide. Self-harm behavior is an attempt to escape from emotional pain. The purpose of the study was to determine characteristic of self-harm behaviour among psychiatric patients visiting outpatients Prof. HB Saanin Mental Hospital in Padang, Indonesia. The research used a descriptive study with a cross-sectional approach. The research instrument is Self-Harm Inventory (SHI), using a sample of 104 respondents with a consecutive sampling technique. The results showed that most respondents were in the age range of 36-45 years (35.6%), male (55.8%), single (49%) and homemakers (28.8%). More than half of patients had senior high school education (54.8%) and diagnosed with schizophrenia (67.3%). Most respondents are in the category of mild self-harm (78.8%), and the most self-harm behavior method is thoughts of attacking oneself. The study concludes that patients in the clinical population (with mental disorders) have self-harm behavior.