Summary: Breast density is positively linked to the risk of developing breast cancer. Furthermore, the addition of breast density as an input to breast cancer risk prediction models has been shown to improve their predictive power. Such models are used in the management of women at high risk but could potentially be used to determine screening strategy. A stepwedge-based technique has been used to measure volumetric density from the mammograms of 1,289 women in the UK screening programme who additionally completed a questionnaire on risk-related factors. The sample had a mean age of 60.1 (range 48.0 - 78.0), a mean breast thickness of 59mm (range 21 - 102mm) and a mean volumetric breast density of 11\% (range 0.5 - 58\%). Using Pearson’s correlation coefficient, breast density was found to be significantly correlated with weight (r = -0.45), body mass index (r = -0.48), age (r = -0.13) and breast thickness (r =-0.65) at the p = 0.01 level. Absolute glandular volume was also found to be significantly correlated with these parameters although the extent of correlation was weaker.