The objective of this study was to evaluate the bone mineral density (BMD) of the proximal tibia in the area adjacent to the fixation of the posterior cruciate ligament (PCL) and compare with the BMD in a similar area at the ideal site for anterior cruciate ligament fixation. Twenty healthy male subjects, undertaking similar daily physical activity were enrolled for this study. The mean age of the subjects was 22 years (range 20-24 years). The bone mineral density (BMD) at the proximal tibia was calculated using a quantitative CT scan of the dominant knee, and the data were recorded in Hounsfield units (HU). Two circular regions of interest, anterior and posterior, of identical diameters (10 mm) and thicknesses (5 mm) were studied. The results showed a significantly higher BMD in the anterior region (162.4 +/- 33.8 HU) than in the posterior one (104 +/- 24.6 HU) with a statistically significant difference (p=0.0001). The clinical implication of this finding is that the fixation should provide a firm construct for PCL reconstructions and be specifically designed for working in low bone quality areas such as the posterior proximal tibia.