During the period 1.1.1984-31.12.1986, primary surgical treatment of 423 women with palpaple, invasively progressing cancer of the breast was performed. All of these had been examined mammographically prior to operation. The uncorrected nosographical sensitivity of the mammographic investigation was 0.93, decreasing to 0.83 prior to the age of 50 years. It is emphasized that patients in whom there is a disproportion between the mammographic and palpatory findings must be referred for surgical assessment without delay.