Most perfume compositions and cosmetics contain mixtures of fragrance ingredients, synthetic or extracted from natural sources. Many of these are known to be weak or moderate allergens when tested individually. However, fragrances are one of the most common causes of allergic contact dermatitis to consumer products, ranking second after nickel. As consumers are exposed to mixtures of ingredients when using products that contain perfume, it was suggested that mixtures could enhance induction and elicitation of skin allergy to fragrances. Prediction of skin sensitization to chemicals is crucial for the cosmetics industry. Nowadays, methods to assess skin sensitization hazard replacing the use of animals have been developed and validated for the testing of pure substances. However, there is practically no experience with testing of mixtures. Here we evaluated in a very preliminary approach, and from a chemical reactivity perspective, if the validated DPRA, hapten-peptide reactivity based assay, could be used at a first sight to evaluate the chemical reactivity of mixtures. Two simple binary combinations of fragrance aldehydes were studied, hydroxycitronellal-citral and citral-cinnamaldehyde. Their reactivity towards DPRA peptides was compared with that of the single constituents. In general, the chemical described as the most potent sensitizer was driving the reactivity in the mixtures. Therefore, it could be hypothesized that the DPRA would estimate the mixture chemical reactivity similar to that of the stronger sensitizer component. This will be reinforced by conditions described for the DPRA where the tested chemical or mixture of chemicals will be added in large excess to the peptides.