Peanuts contain many proteins, some of which may cause adverse immunological reactions in atopic individuals. In this study, the main functional compounds of the water-soluble fraction of peanut seeds were identified using ultra performance liquid chromatography (UPLC) separation coupled with high resolution mass spectrometry (Orbitrap). Using two- and one-dimensional electrophoresis, it was revealed that the raw peanut seeds extract contains several protein components of pHi between 3 and 7 and of different molecular weights. IgE immunoreactivity of a patient allergic to this food, realized by 1D western blot analysis, allowed for the detection of allergens. The 1D electrophoresis of the isolated substance of peanuts roasted at 140 °C for 40 min showed roasting-resistant components. Mass spectrometry allowed us to detect the monomeric form of the allergen Ara h1 (conarachin) and its isoforms (P41B and P17). For the allergens Ara h3, Ara h2 and Ara h6 several protein entities were identified: Ara h3/Ara h4, Gly 1, a storage protein, glycinin and arachin Ahy-3 OS for Ara h3, and conglutin-7 for Ara h2 and conglutin for Ara h6. These molecular entities were characterized by a low molecular weight of 16.9 to 71.3 kDa and acidic or neutral pHi. The immunoblotting indicated that the isoform P41B and conarachin were sources of allergy. Specific epitopes were detected: NNFGKLFEVK and NEGVIVKSKEHVEELTKHAKSVSK for the isoform P41B, SSDNEGVIVK for conarachin and REREEDWRQP for the isoform P41B and conarachin. Glycinin (Ara h3) and conglutin (Ara h6) were resistant to heat treatment, unlike the isoform P17 and conglutin-7 (Ara h2) which were relatively sensitive to this treatment.