Background: Leprosy is one of the infectious diseases of public health importance; it is the leading cause of permanent physical disability as a result of nerve damage. Individuals with leprosy have emotional stress and anxiety, which may lead to both psychological and psychiatric co-morbidity.Objective: This study was conducted to estimate the prevalence of mental distress among leprosy patients attending ALERT Specialized, Addis Ababa, Ethiopia. Method: Institution based cross-sectional study was conducted from April 2011-June 2011. Alternate patients from the daily register of outpatients were interviewed for symptoms of mental distress using the Self Reporting Questionnaire (SRQ-20). This questionnaire was administered by two trained nurses. Data was analyzed using SPSS version 15. Odds ratio were calculated to see the association of dependent variable with each independent variable. P-value <0.05 were considered as statistically significant.Result: The prevalence of mental distress was found to be 30.9%.Physical disability was also associated with mental distress. This study showed that mental distress was significantly higher in patients with leprosy. Conclusion: This piece of study identifies non-specific mental distress. More over the study indicates a need for integration of psychosocial care into current medical treatment. Based on this, future work should be directed at further characterizing the nature and severity of mental disorder in leprosy patients.