Acquired pellicle (AP) acts as a membrane preventing acids from coming into direct contact with the tooth. Possibly individuals with different dental health status present changes in its composition that could disrupt this function. Thus, the aim was to compare the protein composition of the AP in adolescents with Erosive Tooth Wear (ETW), caries or sound. Calibrated examiners in BEWE Index and ICDAS-merged-Epi criteria assessed ETW and caries in a sample of 454 systemically healthy adolescents aged 12 to 15 years old. Thirty subjects from that sample were selected for this study: ETW group (n=10; Total BEWE≥9 and absence of dentinal caries); Caries group (n=10; Total BEWE<9 and with ≥1 dentinal caries lesion), Sound group (n=10; Total BEWE<9 and absence of dentinal caries). Two-hour-formation AP samples were taken from Buccal, Occlusal/Incisal, Palatal/Lingual tooth surfaces. Protein composition was analysed by Liquid Chromatography Tandem Mass Spectrometry. Paired comparisons between groups were done using relative abundances to calculate for protein-fold changes. Two-fold protein increases or decreases were reported (t-test, p<0.05). Gene Ontology-GO- of included proteins was assigned. Mean age of participants was 13.1±1.14 years (56.6% females). The prevalence of ETW was of 66.6% and of dentinal caries of 33.3%. GO analyses showed that the majority of detected proteins were stress-response related. The ETW group disclosed up-regulated relative abundance of Antileucoprotease (2.85-fold in ETW vs. Sound, and 2.34-fold in ETW vs. Caries; p<0.05); Histatin (2.42-fold in ETW vs. Sound, and 2.20-fold in ETW vs. Caries), and Prolactin-induced protein (2.30-fold in ETW vs. Sound, and 2.06-fold in ETW vs. Caries). Hemoglobin subunits Alpha---HBA---and Beta---HBB---showed decreased relative abundances in the ETW and Caries groups when compared to the Sound (HBA:0.42-fold in ETW and 0.40-fold in Caries; HBB:0.45-fold in ETW and 0.38-fold in Caries; p<0.05). AP from individuals with ETW showed differences when compared to other dental conditions. In ETW there was a increase in relative abundance of stress response proteins and a decrease in protective proteins against acid challenges.