Fresh Citrullus colocynthis fruits and leaves were fed to ten sheep at daily doses ranging from 0.25 to 10 g/kg. The sheep showed signs of poisoning and died from 4 hours to 25 days after dosing. The clinical signs of diarrhea, anorexia, dyspnea and loss of condition were well correlated with the pathological findings. There was an increase in the concentrations of creatinine, urea and potassium and a decrease in total protein and calcium in the serum and in the blood sugar level of Colocynthis-poisoned sheep. Changes in the concentrations of serum phosphorus and magnesium were inconsistent. Hematological changes indicated the development of hemoconcentration. Leucocytosis resulted from an increased number of neutrophils.