Testicular germ cell tumors (TGCT) are a heterogeneous group of neoplasms that are divided into seminomas and nonseminomas. Often, they occur as mixed germ cell tumors. In order to make an accurate diagnosis and detect the presence of a certain histological subtype, biomarkers are used as a reproducible source of objective information about the patient's health status. The aim of this thesis was to investigate the specificity of the antigen OCT3/4 (gene POU5F1) and TDGF1 (gene TDGF1) on individual components of TGCT and their potential as diagnostic biomarkers. The methods I used were histological staining, immunohistochemistry, and statistical data processing. After histological staining of tissue sections with hemalum-eosin, a clinical pathologist determined the presence of individual component within the paraffin tissue samples. By immunohistochemical staining of tissue sections from the same histological blocks, analysed was expression of genes of interest at the protein level. Signal quantification in each TGCT component was performed by a clinical pathologist, after which I statistically processed the data. The results indicated a significant expression level of antigen OCT3/4 in cells of embryonal carcinoma, seminoma, and germ cell neoplasia in situ, and TDGF1 in cells of embryonal carcinoma, teratoma, and germ cell neoplasia in situ. The combination of staining for both antigens can distinguish the presence of seminoma in OCT3/4-stained tissues and teratoma in TDGF1-stained tissues.