Though calcium plays an important role in a number of biologic processes related to the pathogenesis of atherosclerosis, the relationship of serum calcium and phosphorus levels with the angiographic severity of coronary artery disease (CAD) is not known. We retrospectively studied 376 stable patients (age range 31-86 years, mean 59.2 +/- 10.5 years; 68% males) undergoing routine coronary angiography and related the angiographic severity of CAD with the serum levels of total and corrected calcium, phosphorus, albumin, total protein and bicarbonate. The primary variable studied was the number of vessels with haemodynamically significant disease. On univariate analysis, total serum calcium and serum albumin levels had a negative association with the number of vessels diseased (P = 0.046 and 0.057, respectively). Multiple regression analysis using age, sex, smoking, diabetes, hypertension, hyperlipidaemia, ethnicity and family history, in addition to serum calcium, phosphorus and albumin levels as the predictor variables, showed that serum albumin has an independent negative and serum phosphorus has an independent positive association with the angiographic severity of CAD (P = 0.04 and 0.003, respectively; n = 294). Serum phosphorus level also showed highly significant positive associations with the presence of total or subtotal occlusion and with most severe stenosis observed on angiography. A moderate change in the serum level of albumin or phosphorus confers a risk similar to that associated with smoking, as estimated by the odds ratios.