PALB2 has been recently identified as breast cancer susceptibility gene in western populations. To investigate the contribution of PALB2 mutations to Chinese non-BRCA1/BRCA2 hereditary breast cancer, we screened all coding exons and intron-exon boundaries of PALB2 in 360 Chinese women with early-onset breast cancer or affected relatives from five breast disease clinical centers in China by utilizing PCR-DHPLC and DNA sequencing analysis. Some genetic variants identified in the cases were then studied in 864 normal controls with no personal or family history of breast cancer. Two protein-truncating PALB2 mutations, 751C>T and 1050_1051delAAinsTCT, were identified in three separate families, and 751C>T was a recurrent mutation. Neither of them, however, were present in the controls (P=0.025). All the truncating mutations occurred in exon 4 of PALB2, and there were still three unclassified variants were detected in the same fragment. We found that exon 4 accounted for 44.1% (15/34) of the person-times carrying with any variant in our study. PALB2 mutations were responsible for approximately 1% of Chinese women with early-onset breast cancer and affected relatives. Our results suggested that a detection of exon 4 before the assay of the whole PALB2 gene might be a cost-effective approach to the screening of Chinese population.