The effects of gastrectomy, especially total gastrectomy, on the serum levels of 25-hydroxyvitamin D and vitamin D-binding protein and on mineral metabolism were examined. The serum 25-hydroxy-vitamin D levels were markedly decreased in patients with total gastrectomy and Billroth II gastrectomy. Decreased levels of serum vitamin D-binding protein and serum calcium, and increased levels of serum alkaline phosphatase were observed in both patients with partial gastrectomy and patients with total gastrectomy. The results show that vitamin D deficiency could develop in high frequency patients with total gastrectomy and Billroth II gastrectomy, and that deranged mineral metabolism could develop in patients with any type of gastrectomy with or without vitamin D deficiency. The decreased levels of serum vitamin D-binding protein in postgastrectomy patients may be a sensitive reflection of the failure of hepatic protein synthesis.