143 Background: Recent literature highlights the importance of germline genetic testing in prostate cancer (PCa) patients. Surprisingly, a literature review indicates that family history records are incomplete in published studies. Methods: Prospective and complete family history data were gathered from 496 men in a single institution with a personal history of PCa who underwent germline genetic testing using a panel of at least 79 genes (Invitae testing) from 2016-2020. Comprehensive FH were obtained in all PCa patients in this database and analysis of prevalent FH was assessed at the time of sample collection. Age, race, metastastes at any time, and Gleason score were also ascertained. MUTYH heterozygotes were not considered pathogenic. Results: Pathogenic/likely pathogenic variants (PV/LPVs) were not associated with age at diagnosis, race, or presence of metastasis. Men with Gleason scores 8-10 at time of diagnosis were more likely to have PV/LPV ( P= 0.004). One or more first degree relatives (FDR) with any cancer with was not predictive for germline PV/LPVs for men with PCa ( P= 0.96). Analysis of patients with one or more FDR with breast, prostate, ovarian, or pancreatic cancer revealed that only FDR with breast cancer ( P = 0.028) or ovarian cancer ( P = 0.015) was predictive for PV/LPVs. Though one or more FDR with prostate cancer did not predict a PV/LPV in the overall panel, further analysis indicate that a history of a FDR with PCa was predictive for PV/LPV in a DNA damage repair (DDR) gene ( P= 0.044). Conclusions: In men with a personal history of PCa, germline PV/LPVs were associated with a FDR with breast or ovarian cancer. A FDR with PCa was predictive for PV/LPV in DDR genes. These data emphasize the contribution of FH to germline genetic testing results in a cohort with complete ascertainment of cancer in first degree relatives.