The series of experiments reported further investigated the time course relationship of the amnesia for saccharin aversion memory in rats and the inhibition of protein synthesis resulting from cycloheximide (CXM). The first experiment showed that intraventricular CXM injected rats which had been trained 7 hrs after injection had learned the contingency under a considerable inhibition of protein synthesis. However, 1 hr after CXM injection protein synthesis inhibition was 86% and yet there was no amnesia observed 24 hr after training. It was also apparent that there were no marked regional differences in the extent of protein synthesis inhibition after intraventricular CXM. Finally, intracisternal injection of CXM 1 hr before training resulted in amnesia 24 hrs after training although this effect was greater when the injection was performed 7 hr before training. The findings (1) are consistent with Day et al's  suggestion of maximal protein synthesis inhibition at 1 hr post CXM injection with an approximately linear decline thereafter, and (2) provide no support for the involvement of the brain stem nucleus solitarius in taste aversion learning.