Clinical diagnosis of Infections generally is realized by means of serological methods, which detect and identify the specific antibodies in tissue fluids associated to a pathogen like bacteria, virus or exotoxins. Antibodies are proteins present in the tissue fluids of our bodies that aid to the elimination or neutralization of pathogens or antigens. On the other hand, the serological methods require chemical reagents, special sample preparation and are time consuming to detect or identify the antibodies. In this work, samples of human serum have been studied by Raman microscopy. Spectra were obtained at excitation wavelength of 514 nm. The Raman spectra of serum contain multiples bands due to serum components such proteins, amino acids, carbohydrates and carotenoids. The results obtained by Multivariate classification, i.e. principal component analysis (PCA) and Fisher’s linear discriminant, suggest that is feasible discriminate between serum samples with or without antibodies against Toxoplasma gondii. Buy this Article