Diagnostic delay in a group of 189 women with breast cancer was studied and correlated with first symptom, stage of disease, histologic grade and prognosis. Diagnostic delay was divided into patient delay (time from the patient's discovery of a symptom to the first medical consultation) and system delay (time from medical diagnosis to treatment). Patients were divided into five groups by patient-delay time: 0 to 30 days; 31 to 90 days; 91 to 180 days; 181 to 365 days; and greater than 365 days. The median diagnostic delay was 60 days (range, 4-980) and was not influenced by patient age, marital status or nature of first symptom. A consistent and direct relationship was found between delay and tumor size, nodal involvement, presence of metastases, and histologic grade of disease at diagnosis. No correlation was found between diagnostic delay and histologic type distribution. The three-year survival rate after treatment was significantly lower for patients with a longer delay. Our data indicate that diagnostic delay appears to be an important determinant of stage at diagnosis in women with breast cancer and that it has an important influence on survival. In most cases, delay was mainly patient dependent (60 days); the median system-dependent delay was 15 days (range, 4-47). Since early treatment is generally accepted to be one of the most important determinants of prognosis in breast cancer patients, a reduction in diagnostic delay may lengthen survival time.