Background: Active surveillance (AS) is the standard of care for low-risk prostate cancer (PCa). However, there is limited data exploring factors associated with reclassification among non-Hispanic Black (NHB) and Hispanic men enrolled in AS. In this study, we examined factors associated with reclassification among men enrolled in AS within a multiethnic population. Methods: We identified men enrolled in AS from 2005-2019 at our institution, and collected demographic/clinical data. We then compared characteristics among men who experienced pathologic reclassification while on AS vs men who did not. Reclassification was defined as either type 1 (Grade Group (GG) 1 to GG2) or type 2 (GG1 to ≥GG3). Our AS protocol generally consists of biannual prostate specific antigen (PSA) testing and prostate biopsy every 1-3 years. Prostate MRI is used to guide decisions on selective basis. Logistic regression was used to determine factors associated with reclassification. Results: Among 197 men enrolled into an AS protocol within our institution, 133 (67.5%) did not experience reclassification by the end of follow-up while 64 (32.5%) did (Table). Median follow-up time was 12 months (IQR: 7-20), and 2-year overall reclassification-free rates were 59.3% (95% CI: 59.2-59.4). 2-year deferred treatment rates were 26.4% (95% CI: 26.3-26.5) for radical prostatectomy (RP) and 16.9% (95% CI: 16.8-17.0) for radiation therapy (RT). NHB and Hispanic men composed 87 (44.2%) and 70 (35.5%) of our cohort, respectively. Higher PSA at diagnosis was associated with adverse reclassification (OR=1.02, 95% CI: 1.01-1.05, p=0.002), and there was a trend towards NHB men having higher odds of experiencing reclassification (OR=2.78, 95% CI: 0.85-9.10) although the result was not statistically significant (p=0.09). Conclusions: In a diverse, multiethnic cohort, rates of adverse reclassification on AS were relatively low. The only factor predictive of reclassification while on AS was higher median PSA at diagnosis; however, NHB men did have a trend towards a higher odds of reclassification. Our results suggest that men who are NHB or have higher PSA at diagnosis may benefit from increased surveillance intensity, as they are more likely to experience reclassification while on AS.