We report a unique case involving a male breast cancer complicated with leukemoid reaction caused by PEG-rhG-CSF after chemotherapy. A male patient with postoperative breast cancer developed leukemoid reaction induced by prophylactic use of PEG-rhG-CSF after AC-T regimen chemotherapy. Combined with the related literature, we analyzed and summarized the rare complications of clinical diagnosis, treatment, prevention of myelosuppression after chemotherapy and leukemoid reaction in male breast cancer.