A method for in vitro diagnosis or prognosis of testicular cancer in a biological sample from a patient suspected of suffering from testicular cancer, having a step of detecting the presence or absence of methylation of CpG dinucleotides in at least one genomic DNA target sequence of the sample, the target sequence being selected from at least one of the sequences identified in SEQ ID NOS: 1 to 7 or from at least one sequence which exhibits at least 99% identity with one of the sequences identified in SEQ ID NOS: 1 to 7 and the sequences complementary thereto; to the DNA sequences and to the use thereof as a testicular cancer marker.