Weight gain during adjuvant chemotherapy has been reported by several authors. Because increased body weight at diagnosis is associated with an increased risk of disease recurrence, we have assessed the prevalence of weight gain in a series of patients receiving adjuvant treatment, as well as the association of weight gain with type of treatment and risk of recurrence. We first assembled an inception cohort of 237 patients who had all undergone pretreatment evaluation and treatment at one institution, and had already been followed for at least 12 months. Body weight at the start and completion of treatment was recorded, as was type of treatment and status at last followup. Ninety-six percent of patients gained weight during treatment and none lost weight (mean increase 4.3 kg). Weight gain was strongly associated with treatment, and was least in patients receiving single agent chemotherapy, greatest in patients treated with ovarian ablation and prednisone, and intermediate in those receiving combination chemotherapy. There was no association between weight gain and disease recurrence.