A method for fast analysis of ginsenosides in Panax ginseng roots was developed using ultra performance liquid chromatography-time-of-flight-mass spectrometry (UPLC-TOF-MS). The column used was HSS T3 (100 mm x 2.1 mm, 1.8 microm). The mobile phase consisted of 15 mmol/L ammonium formate and acetonitrile, eluted with the gradient program. The separations of 9 ginsenoside standards and ginseng root extracts were achieved. Based on the MS/ MS fragments and accurate masses of the target compounds and with combination of the MS/ MS fragments of the 9 ginsenoside standards, 27 ginsenosides were identified from the extracts of the ginseng roots. The validation of the analytical method was thoroughly investigated with 9 ginsenoside standards. It was found that 9 ginsenosides had a better linearity in 0.04 - 9.00 mg/L. The recoveries at the three spiked levels (low, medium and high) were 90% - 100%, 98% - 104% and 96% - 103%, respectively. The relative standard deviations (RSDs) of the peak area ratio of 9 ginsenoside standards to internal standard at the medium spiked level were not more than 11.3%, which were satisfactory for profiling analysis of herb extracts. This method is characterized by its high resolution, rapidness, simplicity and reliability, and has been successfully applied to the evaluation of the differentiation between 2- and 6-year-old ginseng roots. It can be expected that this method is also useful for the fast determination of the ginsenosides in other ginseng related samples.