Simmondsin, a glycoside from jojoba meal, decreases food intake after oral administration. The present experiments are designed to clarify the mechanism of simmondsin's anorectic activity. The meal pattern analysis shows that simmondsin supplementation at different doses results in a dose-dependent food intake reduction, which is more pronounced after prior simmondsin experience. The effect of simmondsin on meal patterns (decreased meal size, meal duration and eating rate, increased latency to eat) is most severe at the highest concentration. Rats familiar with simmondsin more seriously postpone their first meal than with first contact, resulting in a decrease of the meal frequency and the day/night feeding ratio. Rats given the choice between a control diet and a simmondsin-supplemented (0.5%) diet, after half an hour, have a significant preference for the control diet. Simmondsin seems to have a specific flavor when mixed in the food since rats recognise the feeder containing simmondsin. The ability of simmondsin to induce conditioned taste aversion (CTA) was also investigated. Rats receiving simmondsin at concentrations of 0.15%, 0.25% or 0.5% during their conditioning develop significant taste aversions to the saccharin solutions. The performed experiments indicate that the simmondsin activity shows some analogy with the satiating molecule cholecystokinin (CCK) at first contact, but shows more analogy with the illness-inducing agent lithium chloride (LiCl) after prior experience with simmondsin. Rats familiar with simmondsin avoid simmondsin-supplemented food by directly monitoring its presence, and by learning to relate it to the postingestive consequences of consumption.