By means of a questionnaire, sent to the Portuguese hospitals which diagnose and treat most female patients with breast cancer, it was intended to assess the situation regarding the diagnosis of carcinoma in situ and early breast cancer (Tl or T2, NO or NI), as well as their evolution between 1985 and 2000. The hospital participation rate was 65% and a sample of 865 patients was collected, distributed in the years 1985, 1990, 1995 and 2000. It was found that the presentation form of breast cancer in 1985 was of palpable tumour in 87% of the cases, whereas in 2000 this situation only corresponded to 54% of the patients, being most of the remaining patients diagnosed by imaging without palpa­ble tumour. In 94% of the patients, the first diagnostic investigation was mammography, associated or not to echography, and the second most frequent investigation was fine-needle aspiration biopsy. The time evolution of the tumour size showed an increasingly earlier diagnosis. Invasive tumours not more than 1 cm represented 13.2% in 1985 and 20.3% in 2000. On the other hand, breast cancers more than 2 cm and not more than 5 cm decreased from 67.2% in 1985 to 40% in 2000. When oncology centres and some large university hospitals (Group A) were compared to the other hospitals (Group B), there were no significant differences between the diagnostic methods, although the sequence of diagnostic methods was different in the hospitals in Group A versus those in Group B. It was observed that in more differentiated hospitals the diagnosis was achieved increasingly earlier along the studied periods, and this situation did not occur in the other hospitals.