Four female fistulated camels (Camelus dromedarius), 4-5 years of age, were each given two grams of 10% monensin intraruminally daily for six days to study the effect of monensin on the rumen fermentation pattern. Signs of toxicity appeared on the sixth day, and included depression, anorexia, muscular weakness, inability to stand, salivation and regurgitation of ruminal contents. On the eighth day, two animals died. The ruminal contents were replaced in the survivors, but they died on the tenth and eleventh day from the start of the experiment.