Sub-acute ruminal acidosis (SARA) is a well-recognized digestive disorder that is an increasing health problem in most dairy herds. Feeding diets high in grain and other highly fermentable carbohydrates to dairy cows increases milk production, but also increases the risk of SARA. Sub-acute ruminal acidosis is defined as periods of moderately depressed ruminal pH, from about 5.5 to 5.0. Sub-acute ruminal acidosis may be associated with laminitis and other health problems resulting in decreased production. Dairy herds experiencing SARA will have a decreased efficiency of milk production, impaired cow health and high rates of involuntary culling. Reduced ruminal efficiency, liver and lung abscesses, and laminitis are all thought to be related to SARA. The risk of developing SARA can be reduced by adopting a feeding regime, which balances ruminal buffering with the production of volatile fatty acids from fermentation of carbohydrates. Recommendations made for effective characterization, important management factors and good management practices of SARA in dairy cattle are further highlighted.