Inherited mutations in PALB2 are known to be associated with increased breast cancer risk. We aimed to investigate the prevalence and risk association of a recurrent PALB2 mutation, c.509_510delGA, among 3,924 unselected breast cancer patients from Belarus, Russia or Germany. High-resolution melting analyses and direct sequencing identified the c.509_510delGA allele in 3/1,008 (0.3 %) German breast cancer patients, 2/994 (0.2 %) Russian breast cancer patients and 5/1,922 (0.3 %) Byelorussian breast cancer patients. Breast tumours were mainly estrogen receptor positive and included both ductal and lobular histology. Only one of the ten patients had a first-degree family history of breast cancer. The mutation was not detected in 2,827 healthy females from the same populations, confirming the association of PALB2*c.509_510delGA with breast cancer risk (p = 0.007). These data indicate that the PALB2*c.509_510delGA mutation is prevalent in about 1 in 400 breast cancer patients from Central and Eastern Europe, and the low occurrence of familial clustering is consistent with a moderate penetrance of this mutation.