Loracarbef concentrations in plasma and middle ear fluid (MEF) were measured in specimens obtained approximately 2 h after doses of 7.5 or 15 mg/kg. The mean +/- standard deviation concentrations in MEF were 2.0 +/- 2.6 mg/liter (48% of the concentration in plasma) after the smaller dose and 3.9 +/- 2.6 mg/liter (42% of the concentration in plasma) after the larger dose. With the larger dose, the concentrations in MEF were greater than the MIC for 90% of strains of the usual pathogens of acute otitis media tested in 16 of 17 specimens.