A retrospective study of consecutive radically operated stage II postmenopausal breast carcinoma patients diagnosed in Oslo 1980-1989 is presented. The primary aim was to analyse to which extent the increasing knowledge of the new life-prolonging treatment with adjuvant tamoxifen influenced the clinical routine, and how the national recommendations were followed up. Secondary, the concomitant use of estrogen receptor (ER) analysis during the decade was to be assessed. Eligible were 150 patients without adjuvant treatment, 123 patients with radiotherapy alone, and 158 patients who had received systemic adjuvant hormone therapy. The percentage of patients without any adjuvant treatment decreased from 43% (1980 1983) to 29% (1987 1989) together with decreasing use of radiotherapy. Adjuvant tamoxifen treatment increased from 18% to 51%. In 1989, the year after publication of national recommendations of adjuvant tamoxifen treatment in stage II patients, 43% of the patients who were candidates for adjuvant tamoxifen failed to receive the therapy. Only 58% of all stage II patients had an ER analysis in the study period. The low compliance to a scientifically proven and publicly recommended adjuvant treatment of patients with stage II breast carcinoma is disappointing, as is the low performance of ER determination. To reduce the delay of implementation of new treatment modalities in the management of breast carcinoma a strict quality assurance program is needed.