The recovery of brain noradrenaline (NA) from a single dose of 100 mg/kg pyrazole was rapid, but after 500 mg/kg brain NA levels were still maximally reduced 3 days later and did not return to normal until 7 days after injection. The consumption of water followed a similar time course at this dose. Sub-acute experiments were carried out in two sets of animals: those with free access to food and water throughout the experiment and those which during the latter half of the experiment received a known, restricted quantity of food and fluid by gastric intubation. Diet restriction did not alter the pyrazole induced decrease in brain NA and potentiated the decrease observed in the heart. A significant increase in brain 5-hydroxyindoleacetic acid was observed with pyrazole 100 mg/kg in both diet schedules. In addition to the disturbances in food and water consumption, pyrazole also caused a decrease in locomotor activity which was only partly due to the starvation. Rectal temperature did not change. At the higher pyrazole dose in the rats fed by intubation there was incomplete emptying of the stomach. It is concluded that these many changes demonstrate the non-specificity of pyrazole and caution is advocated in its use combined with ethanol in research on experimental alcoholism.