Updated project metadata. We developed a discovery-validation mass-spectrometry based pipeline to identify a set of proteins that are regulated in serum of patients with cervical intraepithelial neoplasia (CIN) and squamous cell cervical cancer using isobaric Tags for Relative and Absolute Quantitation (iTRAQ®), label-free shotgun and targeted mass-spectrometric quantification. At the discovery stage we used a “pooling” strategy for the comparative analysis of immunodepleted serum from patients with early-(CES) and late-stage (CLS) cervical cancer versus healthy controls that revealed 15 up- and 26 down-regulated proteins. The analysis of a new of non-depleted serum samples from patients with CIN, CES, CLS, and healthy controls showed significant changes in abundance of alpha-1-acid glycoprotein 1, alpha-1-antitrypsin, serotransferrin, haptoglobin, alpha-2-HS-glycoprotein and vitamin D-binding protein. To further validate our findings we developed a fast UPLC/MRM method for the simultaneous targeted quantification of these proteins in a new set of 48 CIN, 50 CES, 34 CLS and 48 healthy controls as well as 49 serum samples from patients with ovarian cancer. The panel of six proteins showed 62% sensitivity and 82 % specificity for discrimination of patients with CIN grade 2 or worse from healthy controls, a stage of the disease where current protein-based biomarkers fail to show any discrimination.