Male and female rats of the S1 and S3 strains (descendants of the Tryon strains) were injected with either 1.0 mg/kg of 1757 I.S. (1-5-di-phenyl-3-7-diazadamatan-9-01) or a control solution immediately after each daily trial in a 6-unit alley U maze. One half of the rats received a food reward in the goal box and one half was not rewarded. The nonrewarded drug and control rats did not improve in performance. Both of the rewarded groups improved, and the 1757 I.S.-injected rats made significantly fewer errors than the controls. The drug injections were then discontinued and all rats were given 5 rewarded trials (one per day), each followed by a control injection. On the last 5 trials the mean errors of the rats previously given posttrial 1757 I.S. injections were significantly lower than those of the controls. Further, performance on the last 5 trials was not influenced by the reward condition on the first 5 trials. These results were interpreted as providing further support for the hypothesis that 1757 I.S. improves learning by enhancing memory storage processes.