The underutilization of calcium and vitamin D supplements in the prevention and treatment of osteoporosis is common among high-risk elders. Less is known about the prevalence and adequacy of calcium and vitamin D use by the general population of older adults. We performed a retrospective chart analysis of 617 women and 383 men over the age of 60 (mean age 73 +/- 9 years) seen at an internal medicine practice to establish the prevalence and evaluate the adequacy of calcium and vitamin D supplementation. Adequate supplementation was defined according to the National Osteoporosis Foundation guidelines and the National Institutes of Health Consensus Development Panel on Osteoporosis. Osteoporosis or osteopenia was documented in 207 (33.6%) women and 21 (5.5%) men (P < 0.01). Of 383 men, 116 (30.3%) used calcium, 25 (6.5%) used adequate doses of calcium, 109 (28.5%) used vitamin D, and only 8 (2.1%) used adequate doses of vitamin D. Of 617 women, 415 (67.3%) used calcium, 199 (32.3%) used adequate doses of calcium, 347 (56.2%) used vitamin D, and 83 (21.7%) used adequate doses of vitamin D. When compared with women, men were less likely to be on calcium (OR 0.21, 95% CI 0.16-0.28), on adequate calcium replacement (OR0.15, 95% CI 0.11-0.23), on vitamin D (OR 0.32, 95% CI 0.25-0.42), and on adequate vitamin D replacement (OR 0.13, 95% CI 0.07-0.26). Calcium and vitamin D were greatly underutilized among older patients in an internal medicine clinic. Inadequate replacement doses were common, and men were particularly susceptible to undertreatment.