Abstract: The invention relates to a diagnosis kit, a DNA chip, and to methods for diagnosing or supervising the treatment of testicular cancer, which are of greatest importance, in particular, within the scope of cancer prevention and post-treatment. The invention is essentially characterized in that the mRNA of testicular tumor markers is detected in a blood sample, whereby the tumor markers depict a tumor-associated gene expression. To this end, particularly ?-hCG, AFP, PLAP or GCAP come into question. The detection of the mRNA is carried out by reverse transcription in cDNA and by subsequently amplifying selected segments of the cDNA by means of polymerase chain reaction.