OBJECTIVES. Hyperhomocysteinaemia is an independent risk factor for cardiovascular disease. We explored possible determinants of plasma homocysteine and cysteine concentrations amongst middle-aged and elderly subjects. DESIGN AND SUBJECTS. Of 501 35-95-year-old randomly selected residents of Lund and Malmö, Sweden, 244 (49%; 131 men, 113 women) were investigated. RESULTS. Total plasma homocysteine concentrations were higher in men than in women (mean +/- SD: 13.9 +/- 4.1 and 12.3 +/- 4.1 mumol L-1; P