The investigators aim to perform a prospective, randomised study assessing the impact of alendronate on cardiovascular and bone mineral parameters. This will be a single-centre study involving subjects with CKD Stage 3 (those patients with GFR between 30 and 59ml/min). Arterial stiffness (by pulse wave analysis and pulse wave velocity) and vascular calcification (using CT scans through superficial femoral artery) will be followed as well as serum markers of calcium, phosphate and PTH. Differences in these end-points will be compared between participants taking alendronate and those not. The study will be conducted over a 12 month period and the investigators aim to recruit about 50 patients (25 on alendronate and 25 control).