Midazolam is a water-soluble benzodiazepine that is used for sedation and as an anesthetic coinduction agent in cats. 21,28,37 Similar to other benzodiazepines, midazolam is considered to cause minimal cardiovascular or respiratory depression and provides good muscle relaxation. 10,35 The rapid elimination halflife of midazolam in dogs (28 to 31 min) 35 and humans (1.5 to 3 h) 33 makes midazolam a more suitable agent for use in continuous infusion than diazepam. 10,33 In humans, midazolam is considered to have a wide margin of safety in comparison to other drugs in this class 33 and is often administered through continuous infusion for patients in the critical care setting. 16,29,34 Midazolam is a useful adjunctive agent during general anesthesia in dogs, 15,39 rabbits, 17 and goats, 12 primarily through the reduction of the minimum alveolar concentration (MAC) of inhalant anesthetics or as part of a total intravenous anesthetic technique. Continuous infusion of midazolam in cats has been reported in only one prior study; 6 however, plasma concentrations were not measured. At present, there is no published report on its effects on MAC in cats. Therefore, we designed a pharmacokinetic evaluation and a subsequent pharmacodynamic study to investigate the sparing effects of 3 midazolam infusion rates on the minimum alveolar concentration of sevoflurane that prevented movement in response to noxious stimulation (MAC NM) in cats. Adverse effects from midazolam administration in cats occur infrequently. In some experiments, a wide range of midazolam doses (from 0.05 to 20 mg/kg IV) have been administered to cats. 19,26 Paradoxical behavior such as increased aggression, restlessness, and increased appetite have been described to occur with administration of midazolam even at low doses. 5,19 Sedation, ataxia, and recumbency have also been observed, but treatment is usually neither indicated nor attempted .6,20,21 During the start of our pharmacodynamics study, the occurrence of prolonged and recurrent sedation in 2 of the 6 cats, despite administration of the specific reversal agent (flumazenil), ultimately prompted discontinuation of the study. The clinical signs and treatment outcomes for those 2 cats are described here.