Concentrations of serum calcium and inorganic phosphate and serum alkaline phosphatase activity have been determined in 75 males over the age of 60 years and 40 young adult controls. Serum calcium and inorganic phosphate levels were significantly lower in the elderly group. Serum calcium-inorganic phosphate product was below 30 in 36% of the aged individuals. Serum alkaline phosphatase activity was elevated in one subject only. These results indicate the existence of mild vitamin D deficiency in the elderly males in this region.