Sugar beet pulp, a major by-product of the sugar industry, is a common feed component in cattle diets that is preserved on-farm as silage. This study was designed to investigate if sugar beet pulp silage could be a vehicle of common mycotoxins found in silages and other regulated mycotoxins. Samples (n = 40) favouring mouldy spots, if present, on the front face of open silages were collected in 2011 from 5 regions representing the main French sugar beet producing areas. Mycotoxins were extracted by QuEChERS procedure without any further clean-up and analyzed by liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC–ESI–MS/MS). The mycotoxins monitored were: aflatoxin B1, deoxynivalenol, gliotoxin, ochratoxin A, mycophenolic acid, patulin, penicillic acid, roquefortine C and zearalenone. Matrix-matched calibrations were used, yielding acceptable levels of recovery ranging from 64 to 168%, except for gliotoxin and roquefortine C for which recovery was lower (21 and 34%, respectively). Eight samples out of 40 (20%) were found to be positive. Mycophenolic acid and zearalenone were the most predominant of the mycotoxins studied. Mycophenolic acid was found in five of 40 samples at levels ranging from traces up to 1436 μg/kg. Zearalenone was found in three samples at concentrations of 1023, 4862 and 6916 μg/kg. The last 2 samples were at concentrations above the recommended limit of 2000 μg/kg. Ochratoxin A was detected in one sample at 15 μg/kg, which is below the recommended EU limit of 250 μg/kg. Roquefortine C was also detected but at low levels. To our knowledge, this study is the first to report on the presence of mycotoxins in sugar beet pulp silage. Contamination for the tested mycotoxins was low and did not seem to present a health risk for animals or consumers for the tested mycotoxins.