Serial quality of life (QL) assessments are being obtained every 3 months for 2 years from patients with operable breast cancer in two ongoing International Breast Cancer Study Group (IBCSG) randomised clinical trials of adjuvant treatment. The QL-assessments include patient-derived perceived coping (PACIS, personal adjustment to chronic illness scale), well-being (Bf-S, Befindlichkeitsskala von Zerssen), mood, physical well-being and appetite (LASA, linear analogue self assessments). The first assessment within 6 weeks of surgery was performed by 70% of the patients. The analysis of serial assessments for 265 patients with each of the first four assessments completed showed that all measures improved with increasing time from study entry; that the degrees of improvement for the four major language groups were similar; and that measures were sensitive to treatment difference. In conclusion, measurement of QL related aspects in a multicultural clinical trial is feasible and possibly relevant for the evaluation of treatment results.