Calf pulp was treated with full-strength formocresol, diluted formocresol, or saline for 4 hours. After washing and homogenization, the water extractable supernates were analyzed for total amino acid, carbohydrate, and hydroxyproline content. Additional samples were tested against trypsin, pepsin, collagenase, and hyaluronidase. Other tissue samples treated with 1/5, 1/10, and 1/25 dilutions of formocresol were subjected to trypsin and collagenase. The control tissue gave 50 per cent more extractable material, which contained over 300 per cent more total amino acids and hydroxyproline but only slightly more carbohydrate than the treated tissue. Formocresol treatment produced an 80 to 90 per cent reduction in reactivity to trypsin, pepsin, and collagenase but little change from hyaluronidase action. The increase in reactivity of the tissue to enzyme hydrolysis paralleled the increase in dilution of formocresol. These results indicate a profound effect on the protein fraction of pulp exposed to full-strength formocresol.