Objective: The main objective of this study was to investigate the pharmacokinetic characters of eszopiclone (CAS: 138729-47-2) after single and multiple-dose oral administration in healthy adult Chinese volunteers. Methods: In single-dose study, 12 subjects were given oral administrations of 1.5, 3 and 6 mg eszopiclone in an open-label, randomized, crossover fashion. In multiple-dose study, 8 subjects were given 3 mg eszopiclone once daily consecutively for 7 days. Blood samples were collected over 24 h and plasma eszopiclone were determined using a validated liquid chromatography/mass spectrometry (LC/MS/MS) assay. The safety and tolerability of eszopiclone was evaluated by adverse events recording, physical examination, laboratory testing, vital signs, and 12-lead ECG findings. Results: The main pharmacokinetic parameters of eszopiclone after single-dose administration were as follows: doses of 1.5, 3 and 6 mg; C-max of 18.08 +/- 4.65, 38.29 +/- 15.41 and 76.38 +/- 23.34 ng/ml; T-max of 0.94 +/- 0.39, 1.04 +/- 0.63 and 1.08 +/- 0.51 h; AUC(0-24) of 110.90 +/- 23.06, 22736 +/- 62.41 and 504.10 +/- 140.13 ng*h/ml; elimination half-lives of 5.84 +/- 1.03, 5.53 +/- 1.91 and 6.17 +/- 1.23 h. After multiple-dose administration, the steady-state levels of eszopiclone were achieved by the 4th day, and the maul pharmacokinetic parameters were C-ss_max at 33.43 +/- 5.63 ng/ml and AUC(ss (0-24)) at 263.30 +/- 51.21 ng*h/ml. The most common adverse event was bitter or abnormal taste. All the adverse events were judged as mild to moderate and resolved without any medication. Conclusion: The pharmacokinetic character of eszopiclone is linear and dose-proportional over the range of 1.5-6 mg. The systemic exposure does not accumulate with once-daily administrations. Eszopiclone appears to have good safety and is well tolerated.