In an effort to identify improved methods for diagnosis of infection in the neonatal foal, clinical records from 38 septicaemic foals of less than one week of age were examined for trends in history, physical examination and clinicopathological findings. The survival rate of septicaemic foals, 26 per cent, was markedly less than the rate for all other foal admissions. Blood cultures were valuable in diagnosis and treatment of septicaemia and identified a preponderance of Gram-negative infection. Zinc sulphate turbidity test results were abnormally low in all septicaemic foals tested. The clinical course was often distinguished by severe complications and multiple organ dysfunction, leading to death. Conditions present in the mare pre-partum resulted in weak or diseased foals; bacterial placentitis, vaginal discharge and premature lactation were most common. There was no single diagnostic criterion of the septicaemic foal. Fever was not a consistent finding. The most useful white blood cell parameters were neutropenia, the presence of band neutrophils (greater than 0.2 × 109/litre) and toxic changes in the neutrophil population. Hypoglycaemia, metabolic acidosis and hypoxaemia were also common findings.