Aim: To present a rare case of a patient with an isolated brain metastasis from colorectal carcinoma in whom an extensive diagnostic workup failed to identify the primary tumour. Case report: A 73-year-old female patient was admitted to the Neurology Department due to weakness in the right side of her body. Imaging with multislice computed tomography (MSCT) and brain magnetic resonance (MR) confirmed an expansive lesion in the left frontal region with surrounding oedema. Radiological findings suggested either a metastasis or a high-grade primary glioma. As the diagnostic workup did not reveal the primary tumour, the patient was transferred to Clinical Hospital Dubrava for surgical treatment. An intracranial tumour resection was performed with a histopathological confirmation of colon carcinoma metastasis. Postoperative brain irradiation was administered. A positron emission tomography scan (PET) showed focal accumulation of radioisotopes without clear pathological substrate in the appendix and cecoascedent junction area. Repeated colonoscopy did not find any pathological mucosal changes. The patient declined systemic treatment. Overall survival was 11 months, in line with literature data. Conclusion: The diagnosis of brain metastases from colorectal carcinoma is very rare, and even rarer is the diagnosis of isolated brain metastases without extracranial progression, counting for <0.5%. Therapeutic options for brain metastases from colorectal carcinoma include surgery, radio-neurosurgery, stereotactic radiotherapy, and brain irradiation. In our opinion, diagnostic evaluation of the central nervous system in patients with colorectal carcinoma should be considered if the patient has neurological symptoms or if there is an increase in carcinoembryonic antigen (CEA) levels without signs of extracranial disease progression.