LEAD POISONING impairs memory and learning. The protective effect of natural zeolite CLINOPTILOLITE on memory and learning impairment in RATS exposed to lead acetate was investigated. 60 male Wistar RATS in six groups treated for 2 months with diets contained different ratios of natural zeolite (ie 5% or 12.5%), and% 0.2 lead acetate (LA) concentrations. behavioral test was evaluated by passive avoidance learning method in shuttle box at 6, 12, 24, 48 hours, and one week after the shock test. digestive exposure with 0.2% lead acetate in the presence of zeolite additive had no effect on the RATS’memory performance (P & lt; 0.05). Adding 5 and 12.5% w/w of natural zeolite to the RATS’feed improved short-term, medium-term, and long-term memory performance (P & lt; 0.05) compared to the control group. observed improvement in memory function can be considered in part as the indirect effects of cation exchange or adsorption property of ZEOLITES.