The prevalence of breast cancer at Dr. Moewardi Hospital is currently ranked first on oncology cases at 18.92%. Chemotherapy is effective in fighting cancer cells, reducing tumor size, and giving a good prognosis in patients. Side effects of chemotherapy are indigestion with a manifestation of decreased food intake which has an impact on nutritional status and hemoglobin levels. Risk factors causing anemia are chemotherapy cycle, body mass index (BMI), age and initial hemoglobin. Objective: To determine the predictive factors of anemia caused by chemotherapy. Method: observational with cross sectional design. Subjects of the study were 115 patients aged 30-60 years who were taken randomly. Multivariate analysis with logistic regression to find the basic risk factors for anemia. Results: Anemia prevalence was 87%. The occurrence of anemia was significantly associated with four risk factors: Chemotherapy cycle (OR=0.282; 95% CI=0.078-1.015;p=0.053), BMI (OR = 7.544; 95% CI=0.962-59.174;p=0.054), Age (OR=0.925; 95% CI=0.396-2.180;p=0.865), Hb at baseline (OR=2.0; 95% CI=1.539-2.599;p=0.001). Conclusion: Identification of chemotherapy risk factors such as chemotherapy cycles, age, BMI, and Hb levels are important for patients at risk for anemia. These risk factors Hb at baseline are significantly associated with anemia in chemotherapy patients.