We present an unusual case of localized colorectal carcinoma complicated by sepsis which was treated with activated protein C (APC). Shortly after treatment the patient developed symptomatic metastases to the bone marrow (BM). Destruction of bones by colorectal cancer (CRC) is rare, although BM micrometastases are frequently observed. However, overt symptomatic BM metastasis is an exotic rarity. APC interacts with molecules and modulates pathways that are unquestionably involved in tumorigenesis and formation of metastases. Therefore a possible contributory role of the anti-inflammatory and immunomodulatory therapy in the rapid evolution of the disease cannot be excluded. Questions concerning the relevance and contribution of sepsis, treatment with APC, exquisitely high levels of non-thrombosis-associated D-dimer and CA19-9 to this highly uncommon course of disease are discussed. The lesson learned from this case is that APC may have contributed to the massive invasion of BM by colonic cancer cells in our patient and that APC should therefore be used with extreme restraint in patients with potentially curable cancer.