We have performed differential screening of a human metastatic lymph lymph node cDNA library to identify genes possibly involved during breast cancer progression. We have identified four novel genes overexpressed in malignant tiddues. They were all located on the long arm of chromosome 17, in loci located between q11 and q21.3, a region known to contain the c-erbB-2 oncogene and the BRCA1 breast carcinomas, and overexpression of three of them was dependent on gene amplification in breast cancer cell lines. These findings further support the concept that human chromosome 17 specifically carries genes possibly involved in breast cancer progression.