The hypothesis that obesity plays a role in the prognosis of breast cancer is examined in this preliminary analysis of a follow-up study of 472 early-stage breast cancer patients. The 75th percentile values of weight (= 73 kg) and body mass index (BMI = 28) in the total patient population were taken as the cut points for estimating overweight or “obesity”. Stratified, survival, and logistic regression analyses showed that increased weight or BMI, but not height, were associated with increased risk recurrence. In the logistic regression analysis, after accounting for other risk factors, stage III was a negative prognostic indicator of recurrence (with stage I as the referrent group, OR = 3. 46, 95% Cl: 1.36–8.81). Women whose weights were above the 75th percentile value had a significantly increased risk of recurrence in relation to the other women (OR = 3.55%, 95% Cl: 1.65–7.65). Results from a model substituting BMI for weight showed a similar significant result. The adequacy of using anthropometric indices as proxies for obesity and various biological mechanisms, which may explain the relationship, are discussed.