In experiments with rats, which were undergoing priming by mouth with an acetic lead solution at the rate of 6 mg/day for 1 1/2 month, the prophylactic effect of apple pectin esterified to the degree of 26 per cent (doses 36 and 72 mg) and of 32 per cent (doses of 216 and 432 mg) was evaluated. The best prophylactic effect was found to produce pectin with a 32 per cent esterification degree, but in some of rats dysfunction of the gastro-intestinal tract was noted.