Background. Thrombotic microangiopathies (TMA) are relatively rare but severe disorders characterised by non-immune haemolytic anaemia, thrombocytopaenia and organ failure. In patients with metastatic cancer, sporadic forms of TMA can be triggered by chemotherapeutic agents or can occur as complication of malignancy itself or of infections. Case report. Hereby, we report a case of a patient diagnosed with metastatic colorectal cancer who experienced an atypical haemolytic-uraemic syndrome (aHUS) during chemotherapy treatment with FOLFOX6 scheme. The use of eculizumab led to prompt recovery of laboratory parameters that was maintained despite treatment discontinuation due to appearance of pneumonia infectious. Additionally, genetic analyses revealed the presence in heterozygosis of CFH gene polymorphisms associated with aHUS. Conclusion. This case emphasises the importance of considering TMA as a possible diagnosis in patients with cancer presenting with haemolytic non-immune mediate anaemia and thrombocytopaenia associated with worsening of renal function. Prompt diagnosis is crucial for the requirement of its specific treatment that can impact on long-term outcome and prognosis.