The effects of 40 mg/kg Metrazol on a conditioned saccharin aversion produced by LiCl were studied in two experiments. In Experiment 1, it was found that Metrazol administered 10 min before or after LiCl did not impair conditioned aversion to saccharin. In Experiment 2, Metrazol was given 2 min before, 9 or 3 min after the administration of LiCl. Under these conditions, impairment did occur. It was concluded that Metrazol may impair conditioned taste aversion in a time-dependent manner. The present findings are discussed in terms of their relationship to ECS as an interfering agent and retroactive and proactive effects on the CS and/or the UCS.