Cold autoimmune hemolytic anaemia (AIHA) has several causes, including Primary Cold Agglutinin (CAD). The cold AIHA in CAD is due to autoantibody anti-I. Most antibodies in cold AIHA are IgM subtype that optimally binds to red blood cells (RBCs) at 0°C–4°C. The presentation of the primary CAD is variable. Some patients presented with severe hemolytic anaemia and some incidentally had discrepancies in the laboratory results due to the cold agglutinin interferences. Here, we present a case of CAD secondary to clonal B Lymphoproliferative Disease (LPD). The patient presented with fever and had melaena. Upon blood taking for the investigations, the blood was easily clotted and his blood group showed discrepancy results forward and reverse.