Description: The aim of this investigation was determination of main pharmacokinetic parameters of tilmicosin after single subcutaneous application of Tilmovet solutio pro imjectionibus 30 percentage (Biovet LTD Peshtera). Tilmovet solutio pro imjectionibus 30 percentage was applied subcutaneously, as a 10 mg/kg dose, to 8 (4 male and 4 female, Brown Bulgarian breed) clinically healthy calves, aged 1.5 - months, weighing 71.5 to 91 kg. Blood plasma tilmicosin concentrations were assayed by HPLC. The main pharmacokinetic parameters were calculated