Recent research studies have shown that, stigma against people with mental illness is universal. Its impact is fundamentally social and can be devastating affects the treatment and prevention of mental disorders. Stigmatized individuals have been found to face a variety of social and emotional consequences including social withdrawal, loss of productivity, lowered self-esteem and increased levels of negative affect. Stigmatization is now recognized as perhaps the central issue facing all who are attempting to understand, prevent and treat mental illness. This study was a descriptive study aiming to evaluate the effect of internalized stigma on self-esteem and loneliness among mentally ill patients. The study was conducted in inpatient ward of Benha mental health hospital. Four instruments were used for collecting the data, socio-demographic and clinical data sheet, Internalized Stigma of Mental Illness Scale, Rosenberg self-esteem scale and UCLA loneliness scale. A convenience sample of 100 psychiatric patients was recruited in this study. The actual study was carried out through three months. The main results revealed that, there were negatively statistical significance relation between internalizing stigma and self-esteem and show positively with loneliness among studied subjects. The study recommended that there is an urgent need for developing strategies to fight internalized stigma associated with mental illness.