The clinically occult, mammographically detected suspicion of carcinoma requires a surgical biopsy, but to successfully accomplish this, cooperation of the radiologist and surgical pathologist are vital. First, a "map" indicating the optimal site of biopsy must be prepared with allowance made for the difference between the mammographic and surgical positions. Roentgenographic confirmation of removal of the suspicious area by use of special roentgenography equipment and film is required. By "bread loafing" the specimen, followed by repeat roentgenography, the exact site of the lesion may be localized and excised for optimum pathological assessment. Only by this cooperative effort is accurate diagnosis accomplished. An effective technique has evolved during biopsy of over 100 clinically occult lesions.