The present study has assessed the value of clinical examination of breast cancers in a retrospective study of 2,626 cases of operated mammary lesions. Anatomopathology is used as basic reference. The fiability of the cancer diagnosis is 94%, its sensitivity is 90% and specificity 96%. The total error only amounts to 6%, with 2/3 false negatives and 1/3 false positives. The errors are for the most part due to the anatomopathologic nature of the tumor, its size, the area of the body it is situated in and also to the examiner and to the of the patient. Nevertheless clinical examination still remains the first diagnostic step, and is indispensable in all breast pathology.