Abstract: The system provides analogue electronic sensor means, novel mechanical harness mounting means having adjustment means and provided with remote attached monitor control means for sampling breast surface temperature and means for collecting, storing and displaying these data. The system allows breast temperatures to be measured, with great reliability, for periods of an hour or more at any desired rational sampling rate. Collected breast surface temperature data may then be downloaded into a computer for elaboration using proprietary software. Breast surface temperatures are measured at a specific point during the menstrual cycle, determined by progesterone levels in the urine. The data obtained with the instant invention under these conditions enables an investigator to determine, in women who have not reached the menopause, those who are at risk of developing breast cancer at some time in the future and those who are not at significant risk of developing the disease.