To establish a LC-MS/MS method for quantification of chlorogenic acid, caffeic acid, 3,4-DCQA, ferulic acid and cinnamic acid in rats plasma and study its pharmacokinetics after administration of Mailuoning injection at a single dose to rats. Plasma samples were acidified with hydrochloric acid and extracted with ethyl acetate. The analytes were determined by LC-MS-MS using a ZOBAX SB C18 column with a mobile phase of methanol-water (containing 2 mmol x L(-1) ammonium acetic) (60:40)at a flow rate of 0.5 mL x min(-1) and detected using ESI with negative ionization mode. Ions monitored in the multiple reaction monitoring (MRM) mode were m/z 353.1/191.0 [M-H]- for chlorogenic acid, m/z 178.9/134.9 [M-H]- for caffeic acid, m/z 515.2/353.0 [M-H]-for 3,4-DCQA, m/z 193.0/133.9 [M-H]-for ferulic acid, m/z 146.9/102.9 [M-H]- for cinnamic acid and m/z 246.0/125.8 [M-H]- for tinidazole (IS). After administration of Mailuoning injection at a single dose to eight Sprague-Dawley rats, the concentrations of chlorogenic acid, caffeic acid, 3,4-DCQA, ferulic acid and cinnamic acid in plasma were determined by LC-MS/MS method. The main pharmacokinetics parameters of measured data were caluculated by using DASver 1.0 software. The linear concentration ranges of the calibration curves for chlorogenic acid, caffeic acid, 3,4-DCQA and cinnamic acid were 2.006-1,027 microg x L(-1) (r = 0.999 6), 1.953-1,000 microg x L(-1) (r = 0.999 7), 28.51-1.459 x 10(4) microg x L(-1) (r = 0.998 9), 1.836-940.0, g x L(-1) (r = 0.997 7) and 4.780-2,447 microg x L(-1) (r = 0.998 6) respectively. The inner and inter-days relative standard deviations were both less than 5.0%, indicating legitimate precise and accuracy to the requirement of biological sample analysis. For chlorogenic acid, the pharmacokinetic parameter t1/2, AUC0-t, and CL were (49.78 +/- 12.81) min, (123.55 +/- 14.82) mg x min x L(-1) and (0.004 3 +/- 0.000 5) L x min(-1), respectively. For caffeic acid, the pharmacokinetic parameter t1/2, AUC0-t, and CL were (36.65 +/- 10.59) min, (91.67 +/- 11.77) mg x min L(-1) and (0.005 7 +/- 0.000 7) L x min(-1), respectively. For 3,4-DCQA, the pharmacokinetic parameter t1/2, AUC0-t, and CL were (50.08 +/- 13.78) min, (278.34 +/- 31.82) mg x min x L-1 and (0.001 6 +/- 0.000 2) L x min(-1), respectively. For ferulic acid, the pharmacokinetic parameter t1/2, AUC0-t, and CL were (51.39 +/- 15.52) min, (34.72 +/- 4.67) mg x min x L(-1) and (0.000 4 +/- 0.0001) L x min(-1), respectively. For cinnamic acid, the pharmacokinetic parameter t1/2, AUCo-t, and CL were (74.42 +/- 18.32) min, (34.63 +/- 4.82) mg x min x L(-1) and (0.007 7 +/- 0.001 1) L x min-', respectively. The assay method is proved to be sensitive, accurate and convenient. It can be applied to the pharmacokinetic study of chlorogenic acid, caffeic acid, 3,4-DCQA, ferulic acid and cinnamic acid.