In a study of 7,608 patients with primary breast cancer patient's and doctor's delay were examined in relation to age, tumour size, grade of anaplasia, and number of positive lymph nodes. The delays were arbitrarily divided into the following intervals: Short (0-14 days), intermediate (15-60 days) and long (> 60 days). The well-established patient and tumour characteristics were shown to have prognostic significance. Similarly the delays showed significant influence on survival. A long patient's delay was associated with an unfavourable outcome, as compared with a short delay. On the contrary, the prognosis was superior for patients with a long doctor's delay compared to those with a short doctor's delay. Overall, when corrected for age, the prognostic value of delay in terms of mortality increased by 24% for a long patient's delay compared to a shorter and by 13% for a short doctor's delay compared to a longer. This indicates that doctors are capable of distinguishing between more and less aggressive malignancies. The study also suggests that all sources of delays should be kept at a minimum.