In a cross-over study of 6 clinically healthy cows in early lactation, injection of 10 mg dexamethasone isonicotinate caused significantly increased plasma glucose for 6 days and significantly decreased milk yield for 1 day. The corresponding effects of 10 mg dexamethasone phosphate + 20 mg dexamethasone phenylpropionate lasted for at least 9 and 7 days, respectively. The therapeutic effect in bovine ketosis of the 2 preparations was measured by analyzing acetone plus acetoacetate in milk sampled daily during 8 days posttreatment. Acetone plus acetoacetate in milk from cows given dexamethasone phosphate + dexamethasone phenylpropionate (n = 11) decreased to normal levels and from the 4th day after treatment was significantly lower than in cows given dexamethasone isonicotinate (n = 12).