With the aim of evaluating bone phosphorus/hydroxyproline ratio (P/Hypro) as an index of osteomalacia, this bone index and the bone mineral content (BMC) have been investigated together with other indices of calcium metabolism in 27 gastrectomized patients. None of the patients had clinically manifest bone symptoms. The mean values of bone P/Hypro, BMC, plasma calcium and plasma magnesium were subnormal; the mean values of serum parathyroid hormone (iPTH) and plasma alkaline phosphatase were elevated. Mean serum 25-hydroxycholecalciferol (25-OH-D) did not differ from normal. A significant positive correlation was found between bone P/Hypro and serum 25-OH-D, but no significant correlation between bone P/Hypro and BMC. Serum 25-OH-D and bone P/Hypro were significantly lower and serum iPTH was significantly higher in a subgroup of 12 patients with no regular supplementary intake of vitamin D. In conclusion, the gastrectomized patients had blood biochemical evidence of a mild vitamin D insufficiency and the low bone P/Hypro values can be explained by mild osteomalacic changes in bone.