Abstract: A method for tumor screening using urine of a mammal, the method includes obtaining a total urine nucleic acid (e.g., DNA) from a urine sample of a mammal, extracting a high molecular weight urine nucleic acid (above 1000 bp) by contacting the total urine nucleic acid with an adsorbent in the presence of a buffer which promotes binding of the high molecular weight urine nucleic acid to the adsorbent, replacing the buffer which promotes binding of the high molecular weight urine nucleic acid with a buffer which promotes binding of the low molecular weight urine nucleic acid to the adsorbent, extracting the low molecular weight urine nucleic acid by contacting with the adsorbent, eluting the low molecular weight urine nucleic acid, and assaying the low molecular weight urine nucleic acid for a presence or absence of a gene sequence specific to a certain type of tumor.