SUMMARY Diabetes, uncomplicated by severe renal damage, was established in ewes, 115–135 days pregnant, by injection of 40 mg. alloxan/kg. body weight. The onset of severe hyperketonaemia was accompanied by loss of appetite and rapid loss of body weight, death ensuing usually after 10–16 days. Blood acetate levels were markedly elevated in the early stages of the syndrome, and declined as feed intake fell. It is concluded that the high levels are a consequence of a block in the metabolism of acetate absorbed from the gut. Levels remained above normal after complete loss of appetite, to a degree correlated with blood ketone level. Fasting blood glucose levels were reduced in pregnant ewes below those of non-pregnant ewes, to a degree which correlated with foetal weight. Hypoglycaemia was recorded in fasting diabetic ewes with triplets. Plasma cortisol levels were only slightly increased after alloxan, except in pre-mortal stages, when very high values were associated with terminal increases in blood glucose, NPN and creatinine levels. A dose of 20 mg. alloxan/kg. temporarily increased blood glucose levels and induced a transitory diabetes in two of twelve ewes. Hyperglycaemia and mild ketosis occurred, but were not associated with loss of appetite or loss of body weight. A dose of 60 mg./kg. induced a diabetic-uraemic syndrome in three of eight ewes, characterized by gross elevation of glucose, NPN, creatinine, amino-N and cortisol levels. This syndrome occurred in only two of sixteen ewes after 40 mg. alloxan/kg.