Prolactinomas are the most common type of functional pituitary tumors. Dopamine agonists is the most important drugs used in prolactinoma,have antagonistic effect with antipsychotic drugs used in schizophrenia. Conversely, dopamine antagonist drugs increase prolactin in patients with simultaneous schizophrenia. In the present case, we report a 29-year-old single male with schizophrenia who treated for 8 years with risperidone and presented with macroprolactinoma. Iatrogenic hyperprolactinemia is a well-known side effect of dopamine antagonist drugs for treatment in a patient with schizophrenia. On the other hand, it appears these drugs have the other side effects, such as drug- induced prolactinoma or boost growth.