BACKGROUND Though breast diseases even in benign status poses considerable anxiety and fear to the suffering woman and to her blood relatives, this leads to extensive investigative modalities in benign breast diseases including MRI and wire localisation of the impalpable lesion and biopsy to prove beyond doubt that it is not malignant. This paper is to enlighten the critical situation to which we were pushed in our analysis of 4 cases of bilateral benign cystic breast diseases who were diagnosed to have malignancy in one of the breasts during periodic followup, while they were on conservative treatment. The interesting facts like-1. Malignancy after wide excision for cystic lesions; 2. Incidence of malignancy in the family, 3 of the 4 patients; 3. Association of HER-2/neu oncogene positivity status in all the patients; 4. Demand and decision to do bilateral prophylactic mastectomy in patients even though the breast lesion proved to be benign. MATERIALS AND METHODS The study was conducted in Vinayaka Missions Medical College, Karaikal and Private Clinic in Thanjavur. A series of 320 cases of benign breast disease of varying ages from 20 to 60 years were studied for a period of 2 years. Diagnosis was made by means of histopathological examination and sonomammogram. Followup was done for a minimum period of 1 year. RESULTS 320 cases of bilateral benign breast disease were studied, out of which 4 cases were found to be malignant during followup. The 4 cases were studied briefly and the results were as follows. 316 cases were found to be benign even after followup for a minimum period of 1 year. 4 cases were found to be malignant during followup. 3 out of 4 patients had family history of breast malignancy. PR + ve ER-2/ neu +ve 1-nulliparous unmarried. All four above the age of 40 years. High risk patients for developing malignancy. CONCLUSION High risk population must be screened routinely. The risk of malignancy is very high following benign breast disease. Other factors such as age, nature of discharge, parity and family history were taken into account and treatment was tailored according to the diagnosis.