Antipsychotic drugs are effective in treating the positive symptoms of schizophrenia; however their efficacy in treating negative symptoms is limited. This study wants to evaluate efficacy of selegiline augmentation of antipsychotic medication to treat negative symptoms in inpatients with chronic schizophrenia. With randomized clinical trial two groups of patients will select to receive selegiline or placebo.

Primary end point is decreasing in negative symptoms in case group. Inclusion criteria : 1- Patients with moderate to severe negative symptoms 2- Patients with at least one year antipsychotic drug therapy, at the current dose >= 1 month. 3- No other psychotropic drugs during past month. Exclusion criteria: 1- Severe major depressive disorder, substance abuse, severe positive symptoms of schizophrenia, Treatment of MDD with antidepressant drugs during past month.

Inclusion Criteria:

• Patients with moderate to severe negative symptoms
• Patients with at least one year antipsychotic drug therapy, at the current dose >= 1 month.
• No other psychotropic drugs during past month

Exclusion Criteria:

• Severe major depressive disorder
• Substance abuse
• Severe positive symptoms of schizophrenia
• Treatment of MDD with antidepressant drugs during past month.