Randomized clinical trials (RCT) are the best way to define optimal treatment, but the accrual rates for hardly any trials have been reported. We analyzed retrospectively the participation of patients in eight phase III multicenter RTCs. Out of a total of 738 patients treated in a single institution for operable breast cancer over a 3-year period, 455 patients (62%) were eligible for at least one of the ongoing trials. Overall, 81% of the patients were informed and 47% of the eligible patients consented to participate. The accrual was 100% to a study with an aggressive combined modality treatment arm for patients with a poor prognosis. A low accrual rate was seen in two trials: 6% in the "elderly" trial comparing tamoxifen only with mastectomy and 10% to the "axilla" trial comparing surgery with radiotherapy to the axilla. The clinicians failed to inform most of these patients about the two trials. In the literature seven of the eight trials were reported; two of them (29%) failed to accrue enough patients.