The absorption of amoxicillin (AMX) administered orally was studied in rats. Male Sprague-Dawley rats received 7, 15, 25 and 50mg/kg of AMX in two dosage forms, a suspension and a solution. Plasma concentrations of AMX were determined by HPLC. When AMX was administered at 7mg/kg, there was no significant difference in C max , T max , AUC and MRT values between the dosage forms. At 50mg/kg, there was no significant difference in the plasma concentrations of AMX, but the C max and AUC values of the suspension were significantly higher than those of the solution. The relationship between dose, and C max and AUC values for the suspension had a good linear relationship, y=0.113642x - 0.05082, r=0.995, and y=0.727784x - 0.56625, r=0.997, respectively. Thus AMX had a linear pharmacokinetic profile at doses from 7 to 50mg/kg after its oral administration as a suspension, and the dosage form affected the bioavailability of AMX.