AbstractLengths of capillaries and epithelial dimensions were measured on tracings of sections of buccal mucosa stained for alkaline phosphatase from rats on a zinc‐deficient diet.The zinc‐deficient animals showed the following increases over controls: length of capillaries, ×2.67; thickness of cell layer, ×1.47; thickness of keratin layer, ×2.82; basal layer length: surface length ratio, ×1.41. Lengthening of the basal layer and the capillaries showed high positive correlations with thickening of the cell layer. Lengthening of the capillaries exceeded the lengthening of the basal layer and the thickening of the epithelium but fell short of the increased anabolic performance of the epithelium as quantitated in previous investi