The history and results of a clinical examination were recorded for 32 spring-born suckler calves which were hospitalised for intravenous fluid therapy. Blood samples were taken before treatment, during treatment and before discharge and analysed for colostral status, total carbon dioxide as an indication of acid-base status, and haematocrit. All the calves were given intravenously 5 to 10 litres of electrolyte solution containing 144 mmol/litre sodium, 4 mmol/litre potassium, 113 mmol/litre chloride and 35 mmol/litre bicarbonate, supplemented, in 24 calves, with up to 450 ml of 1M sodium bicarbonate. Nearly all the calves were recumbent but less than half were dehydrated on admission. The signs of dehydration were well correlated with each other and with the haematocrit. Neither the history nor the clinical signs were useful predictors of acidosis. There was no relationship between the severity of acidosis and the degree of dehydration. Acidosis was more prevalent in older calves (P < 0.01). For the severely acidotic calves, supplementary intravenous fluid with sodium bicarbonate significantly (P < 0.05) improved the total blood carbon dioxide at discharge. All 32 calves recovered. It is possible to treat acidotic calves with intravenous fluid therapy effectively, economically and according to their individual needs. The Harleco apparatus is a simple, useful, cost-effective adjunct to the diagnosis and treatment of this life-threatening condition.