Ganoderic acid A is one of the important active triterpenoid components of Ganoderma lucidum, however the study on pharmacokinetics and oral bioavailability of it is still lacking. The present study aims to investigate pharmacokinetic properties and the absolute oral bioavailability of Ganoderic acid A. A sensitive and selective LC-MS/MS method was developed for the determination of Ganoderic acid A. The validated method was successfully applied to the quantification of Ganoderic acid A in rat plasma after oral and intravenous administrations of triterpenoid extract from Ganoderma lucidum with different single dosages. Ganoderic acid A was rapidly absorbed with the time to maximum concentration (Cmax) <0.611 h after oral administrations for all oral dosage groups. The Cmax after oral administration were 358.733, 1378.20 and 3010.40 ng mL-1 for 100, 200, 400 mg kg-1 dosages, respectively. Area under the concentration-time curve from time zero to the last time point were 954.732, 3235.07 and 7197.236 h ng mL-1 after oral administration for 100, 200, 400 mg kg-1 dosages and 880.950, 1751.076 and 7129.951 h ng mL-1 after intravenous administration for 10, 20, 40 mg kg-1 dosages, respectively. The half-life ranged from 0.363- 0.630 h and 2.183 to 2.485 h after intravenous and oral administration, respectively. Absolute bioavailability ranged from 10.38-17.97%.