Background: Active surveillance (AS) is the preferred management strategy for men with low-risk prostate cancer. However, approximately one in three men on AS experience progression of disease leading to treatment within 5 years, highlighting an urgent unmet need to reliably distinguish indolent from aggressive prostate cancer and improve patient selection criteria for AS. Germline genetic testing for DNA repair gene mutations is now recommended for patients with newly diagnosed prostate cancer and a strong family history of prostate cancer or BRCA1/2-related cancers, as such mutations have been associated with more aggressive forms of the disease. Here, we investigated the impact of family history on AS outcomes, under the hypothesis that men at high genetic risk for prostate cancer are at greater risk for progression to treatment on AS. Methods: We retrospectively reviewed detailed family history data of 958 patients from our institutional database of men enrolled in AS between 1997-2019. Data on family history of prostate cancer and hereditary cancer syndrome (BRCA1/2-related prostate, breast, ovarian and/or pancreatic cancers) were collected and integrated into a composite family history score incorporating the number of relatives with each cancer weighted by degree of relatedness. A strong family history was defined as a composite score representing > 1 first-degree relative equivalent. The primary outcome was biopsy progression and secondary outcomes were adverse pathologic features at prostatectomy and biochemical recurrence. Statistical analysis was conducted using the Kaplan-Meier method and Cox proportional hazards regression. Results: In univariate analysis, a strong family history suggestive of a hereditary cancer syndrome (HR 1.37 [1.03-1.90], P = 0.033) was associated with a significant increased risk of biopsy progression; however, any family history of prostate cancer (HR 1.10 [0.89-1.35], P = 0.38) and a strong family history of prostate cancer (HR 1.35 [0.92-1.98], P = 0.13) were not significant. In multivariate analysis, a strong family history suggestive of a hereditary cancer syndrome remained a statistically significant predictor of biopsy progression (HR 1.42 [1.03-1.96], P = 0.03), after adjusting for age, percent core involvement on initial biopsy and PSA density. No significant association was found between family history and adverse features on surgical pathology or biochemical recurrence. Conclusions: A positive family history suggestive of a hereditary cancer syndrome is associated with an increased risk of biopsy progression on AS and is an independent predictor of biopsy progression. Men with such a family history may still be safely offered AS but should be counseled about the higher risk of progression. Further work to investigate the underlying genetic factors responsible for this increased risk is warranted.