Purpose To identify potential correlates of CRF after curative breast cancer (BC) treatment. The hypothesis was that fatigue would be more severe among women treated with cardiotoxic drugs, with poor physical condition and those who exercised less.Methods Prospective observational cross-sectional design. Fatigue was evaluated through Perform Questionnaire (multi-item, multi-dimensional). Patient-reported assessments and objective information regarding clinical data, physical activity (PA) and physical condition were analysed as potential correlates of CRF.Results 180 women who remained free of disease were recruited. Prevalence of fatigue interfering with quality of life was 43%. Weight, BMI, treatment with trastuzumab and time spent walking one mile were positively associated with fatigue. Age, time from diagnosis, self-reported walking time, basal and recovery heart rate were negatively associated. Previous chemo, radio or hormonal therapy, objectively assessed weekly PA, cardio-respiratory condition, muscular strength and adherence to Mediterranean diet were not associated with CRF. However, an interesting unexpected negative association with nut intake was found.Conclusions CRF is a prevalent problem after BC treatment. Objectively assessed PA, cardiorespiratory fitness and muscular strength did not predict CRF. The association of CRF with trastuzumab and low intake of nuts should be confirmed in further studies. A deeper insight in heart rate variability is warranted. Future research should include longitudinal studies and determination of biomarkers. Implications for Cancer Survivors BC survivors, especially younger and overweight women, should be informed about fatigue as a potential persistent symptom through all stages of the cancer trajectory and into survivorship. They also should be routinely screened for CRF.