Takenouchi-Kosaki syndrome (TKS) exhibits clinical features represented by macrothrombocytopenia, developmental delay, dysmorphic facial features, and deafness. There is little information on the treatment for macrothrombocytopenia in TKS. Splenectomy has been a contraindication for inherited thrombocytopenia. In the case of autoimmune haemolytic anaemia (AIHA) with TKS that we previously reported, AIHA initially resolved with prednisolone; however, it gradually became resistant to drug therapy. We performed splenectomy, and post-operatively, both anaemia and macrothrombocytopenia improved. This is a novel effect of splenectomy for thrombocytopenia in TKS, which suggests that splenectomy could be a treatment option for thrombocytopenia in TKS.