The invention relates to medical biotechnology and can be used in performing tasks associated with identifying a human PRAME antigen, including in immunohistochemical analysis of the expression of a PRAME protein in human tumours and for developing a drug for targeted treatment of PRAME-expressing diseases. The invention also relates to the detection of an epitope sequence of a human PRAME antigen which can be used for producing human antibodies that are highly specific in relation to PRAME. Antibodies or fragments thereof form complexes with the PRAME protein in immunohistochemical samples of tumour tissue, either by western blotting or by flow cytometry, and may be stained with secondary antibodies. The antibodies produced can be used as an anti-cancer drug for treating PRAME-expressing oncological diseases.