A cohort of 85 Chinese breast cancer patients who received adjuvant chemotherapy with doxorubicin and cyclophosphamide was found to have a significantly higher incidence of grade 3 (n=44, 52%) and grade 4 (n=21, 25%) neutropenia when compared with an historic Western cohort. Also noted was a higher incidence of hepatotoxicity (n=8, 9%). When compared to Caucasian patients, the higher myelotoxicity in our patients may be related to ethnic variation in susceptibility to chemotherapy-related toxicity, lower body mass index with higher percentage of body fat composition, and the popular practice of concurrent alternative medicine during chemotherapy. The higher incidence of hepatoxicity was possibly associated with endemic chronic hepatitis B infection in this geographical area.