Aseptic meningitis is demonstrated by the negative bacterial culture in the cerebrospinal fluid (CSF). It is generally caused by autoimmune disorders, drugs, viral infection, and malignancy. Drug-induced aseptic meningitis is a rare disease. It is commonly caused by antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs). This case concerns a 30-year-old female patient with aseptic meningitis after intake of trimethoprim-sulfamethoxazole (TMP-SMX). The patient developed headache, fever, generalized weakness, stiffness of the neck, and vomiting after the 4^th day of starting TMP-SMX treatment for urinary tract infection. Initial laboratory reports revealed normal blood chemistry and negative blood and urine culture. CSF examination showed neutrophilic pleocytosis (neutrophil count-62%), normal glucose level (58 mg/dl), elevated protein level (88 mg/dl), and negative CSF culture. The patient was admitted to our hospital, TMP-SMX was stopped, and was treated conservatively. Her symptoms resolved completely, and she was discharged on the 4^th day in stable condition.