The aim of this study was to investigate differences in the sensitizing potential of 14 mono(meth)acrylates, when tested by the guinea pig maximization test (GPMT) and Freund's complete adjuvant test (FCAT) with an identical, intradermal induction concentration. A new grading classification of the sensitization potential is proposed. Mono(meth)acrylates show a wide range of sensitizing potential. Compared with other (meth)acrylates, methyl methacrylate is a moderate sensitizer. Attention was paid to concomitant sensitization of additives. In 9 of 16 FCATs, concomitant sensitization occurred to the inhibitors hydroquinone and p-methoxyphenol.