Background: Gliosarcoma is a rare, malignant CNS tumor with a very poor prognosis. Gliosarcoma is a variant of glioblastoma multiforme, which is characterized by the presence of both glial and mesenchymal components. The treatment strategy for gliosarcomas has not yet been determined clearly. Case presentation: This case report presents a 23-year-old female patient who complained of increasing headaches, nausea and vomiting, and slight motor weakness in her left arm. An MRI scan of the brain showed a tumor filling the anterior part of the right lateral ventricle and extending into the right frontal lobe. Tumor extirpation was performed. Histology revealed gliosarcoma. Subsequently, the patient received concomitant chemoradiotherapy with temozolomide in the Stupp regimen. Following the fourth cycle of maintenance temozolomide chemotherapy, at eight months after diagnosis, an MRI scan detected progression of the tumor residue. The patient underwent another surgery and then received 10 cycles of second-line chemotherapy in the ICE (ifosfamide, carboplatin, and etoposide) regimen. She completed oncological therapy with minimal toxicity and follow-up MRI scans showed virtually no residual tumor. Another follow-up MRI scan, performed 28 months after diagnosis, demonstrated progression of the tumor residue again. A third tumor resection was performed 29 months after initial diagnosis. Histology again confirmed gliosarcoma. An early postoperative MRI scan showed subtotal resection with a tumor residue in eloquent areas and also suspected implantation metastasis in the spinal canal at the C2 level. From the neurological perspective, the patient was fully self-sufficient, and had only a very mild motor deficit in her left arm. Currently, at 31 months after initial diagnosis, the patient is in a stable condition and fully self-sufficient. Conclusion: Our case report shows that long-term survival can be achieved in a gliosarcoma patient exhibiting all the unfavorable features in clinical-pathological terms. The minimal recommended treatment is maximal resection followed by adjuvant radiotherapy. Our patient also underwent chemoradiotherapy with temozolomide in the Stupp regimen. Recurrence at eight months after diagnosis was managed by a repeat operation and high-dose combination chemotherapy, which kept the disease in remission for 20 months after the initial relapse. The lack of unequivocal rules for chemotherapy provides an opportunity to test less common treatment regimens.