The clinical findings in 37 sheep and goats with acute ruminal lactic acidosis included a disturbed general condition characterised by anorexia, apathy, teeth grinding and muscle twitching, ruminal stasis, and the excretion of soupy or watery faeces. The ruminal fluid of affected animals was milky, had a sour odour and a low pH. There was a predominance of Gram-positive bacteria in smears of ruminal fluid. In comparison with 10 control animals, the rumen fluid of 23 sheep with ruminal lactic acidosis had higher lactic acid and lower volatile fatty acid concentrations. In addition, the affected animals often had haemoconcentration and metabolic acidosis. Treatment included single or repeated transfer of ruminal fluid from healthy cows and, depending on the severity, the administration of antacids, yeast and chlortetracycline, and the intravenous infusion of isotonic sodium chloride and 5 per cent sodium bicarbonate solutions. Of the 37 treated sheep and goats, four died within 24 hours, and three others were euthanased after one, two and three days because their condition rapidly deteriorated. Thirty animals were discharged one to nine days after treatment. Twenty-nine of them (78.4 per cent) recovered completely but one was euthanased later.