An LC-MS/MS (QqQ) method has been developed and validated for simultaneous determination of the following trichothecenes in UHT cow milk: nivalenol (NIV), deoxynivalenol (DON), deepoxy-deoxynivalenol (DOM-1), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), neosolaniol (NEO), diacetoxyscirpenol (DAS), fusarenon X (FUS-X), T-2 and HT-2 toxins. Sample treatment is simple and based on the extraction with acetonitrile (ACN), acidified with 0.2% formic acid, followed by a purification process, adding sodium acetate to the ACN/water extract in order to separate aqueous phase and, consequently, polar components of the milk. Validation of the method for all the 10 mycotoxins was successful; validation parameters taken into account were as follows: limits of detection (LOD) and quantification (LOQ), linearity, precision (within-day and between-day variability), recovery, matrix effect and stability. The LODs were 10.1, 2.5, 1.5, 1.9, 0.1, 0.5, 1.0, 0.08, 0.4 and 0.05ng/mL for NIV, DON, DOM-1, FUS-X, NEO, 3-ADON, 15-ADON, DAS, HT-2 and T-2, respectively. Mean recovery values (obtained in intermediate precision conditions) were between 63.5 and 75.8 (RSDR ≤15%) for all the mycotoxins. All the mycotoxins suffered from matrix effects, especially DON.