Sub-acute ruminal acidosis (SARA) is a common digestive disorder occurring in ruminants which has a great economic importance associated with decreased animal performance, decreased animal productivity and farm profitability. The aim of this study was to study the occurrence of sub-acute ruminal acidosis in Egyptian buffalo calves and investigate the most evidence clinical signs and biochemical changes associated with the disease. This study was carried out on 30 male Egyptian buffalo calves in farm of Veterinary Medicine collage, Suez Canal University, Ismailia, Egypt. 80 blood samples and ruminal fluids from diseased calf (at the onset of the appearance of the symptoms and on the 4th day of the treatment), and 20 blood samples and ruminal fluid from control ones were collected. The clinical signs were complete anorexia with cessation of rumination, yellowish-white diarrhea without systemic changes and ruminal atony. The biochemical analysis showed a highly significant reduction in serum level of potassium and chloride and highly significant increase in serum glucose and lactate level with a non-significant change in serum levels of sodium and total proteins in diseased calves suffered from sub-acute rumen acidosis. Meanwhile, ruminal fluid of diseased calves revealed a highly significant increase in the mean value of lactate level with a non-significant change in sodium, potassium and chloride level. Ruminal fluid of affected calves appeared milky-gray in color, a slight souring odor with an aqueous consistency. In addition, there were a highly significant reduction in rumen pH, the activity of ruminal protozoa (±) and total protozoal count with a highly significant retardation of SAT and MBRT.