Abstract: 6 Mushroom toxins (i.e., α-AMA, β-AMA, γ-AMA, PHD, PCD and PSC) in human blood plasma were determined by UHPLC in hyphenation with MS/MS in tandem. The plasma sample (1.0 mL) was extracted twice in succession with a mixture of CH₃CN and CH₃OH (1+1) (3 mL for each extraction) for 10 min and centrifuged for 5 min in each extraction. The upper extracts were combined, and evaporated to near-dryness by N₂-blowing at 50 ℃. The residue was dissolved and made up to a volume of 1.0 mL with a mixture of CH₃OH and dil. solution of aq. ammonia 5% (volume fraction) (1+4). The solution obtained was filtered through 0.22 μm filtering membrane, and the filtrate was used for chromatographic separation and MS/MS determination. In LC separation, BEH C₁₈ chromatographic column was used as stationary phase, and mixtures of (A) CH₃OH and (B) dil. solution of aq. ammonia 5% (volume fraction) with various ratios were used as mobile phases in the gradient elution. In MS/MS determination, mode of ESI⁺ under weakly alkaline condition and the MRM mode were selected to determine to 6 mushroom toxins. It was found that the linearity ranges of the standard curves of the 6 toxins were same between 3.12 to 125 μg·L^-1, with their lower limits of determination (10S/N) in the range of 2.0 to 5.0 μg·L^-1. Average recoveries of the 6 toxins found by recovery test were in the range of 78.4% to 106%, and values of RSDs (n=6) found were ranged from 2.3% to 14%.