Abstract Background: Ashkenazi Jews have a 1 in 40 chance of carrying a BRCA1 or BRCA2 (BRCA1/2) pathogenic variant. Our prior research has shown that Orthodox Jewish women face unique social, cultural, and religious factors that may influence uptake of BRCA1/2 genetic testing. The aim of our study was to examine the impact of a web-based decision aid (DA) on BRCA1/2 genetic testing intention/uptake in Orthodox Jewish women. Methods: We conducted a pilot study among 50 Orthodox Jewish women in the New York/New Jersey area who were given access to the RealRisks DA and completed surveys at baseline prior to exposure to RealRisks and at 1 and 6 months after exposure to RealRisks. RealRisks is a patient-centered DA that includes family history intake, calculation of personalized breast cancer risk according to the BRCAPRO model, education about the pros and cons of genetic testing, and preference elicitation. The surveys collected information on participant demographics, health literacy, subjective numeracy, perceived breast cancer risk and BRCA1/2 mutation risk, breast cancer worry, stigma, hereditary breast and ovarian cancer (HBOC) genetic testing knowledge, autonomy, decision self-efficacy, decisional conflict, decision regret, and genetic testing intention/uptake. Descriptive statistics and paired t-tests and Chi-squared tests were conducted to assess changes in the study measures from baseline to follow-up. Results: Fifty women completed the baseline survey, 43 (86%) the 1-month survey, and 38 (74%) the 6-month survey. Mean age was 43.9 years (standard deviation [SD] 14.6); 94% had adequate health literacy and mean numeracy score was 4.25 (SD 0.83; range, 1-6). At baseline, 74% of women had adequate HBOC genetic testing knowledge and 52% thought it was likely that they carried an altered BRCA1/2 gene. Compared to baseline, there was a significant increase in HBOC genetic testing knowledge and decrease in decisional conflict at 1 month and 6 months. There was no significant change in decision self-efficacy, autonomy, stigma, or breast cancer worry after exposure to RealRisks at 1-month or 6-month follow-up. The percentage of women who intended to complete or already completed BRCA1/2 genetic testing decreased from 54% at baseline to 30% at 1 month. At 6 months, 21% reported they had completed or intended to complete BRCA1/2 genetic testing at that time. Conclusions: The RealRisks DA was effective at improving HBOC genetic testing knowledge and reducing decisional conflict about HBOC genetic testing; however, genetic testing intention decreased after exposure to the DA. An intervention that directly addresses the religious and cultural issues regarding genetic testing in the Orthodox Jewish community may improve BRCA1/2 genetic testing uptake and adoption of cancer prevention strategies in this population. Such an intervention will likely have to include religious, community, and medical leaders within the Orthodox Jewish community. Changes in study measures over 3 time pointsOutcome MeasuresBaseline Mean (SD)1 month Mean (SD)p-value compared to baseline6 months Mean (SD)p-value compared to baselineHBOC geneting testing knowledge [range, 0-11]6.60 (2.18)7.74 (1.94)<0.0017.24 (2.07)0.050Decision self-efficacy [range, 0-100]56.26 (15.63)55.39 (16.91)0.869Not Assessed (NA)Decisional conflict [range, 0-100]52.45 (28.43)33.93 (28.74)<0.00128.29 (27.64)<0.001Autonomy [range, 0-7]4.21 (1.43)4.36 (1.38)0.680NAStigma [range, 1-7]3.51 (1.15)3.25 (0.98)0.477NABreast cancer worry [range, 1-7]2.23 (1.03)2.27 (0.98)0.7672.26 (1.00)0.889HBOC genetic testing completion or intention to complete (%)54%30%0.02021%0.002 Citation Format: Meghna S Trivedi, Haley Manley, Haeseung Yi, Thomas Silverman, Wendy K Chung, Paul S Appelbaum, Rebecca Starck, Isaac Schechter, Rita Kukafka, Katherine D Crew. Evaluation of a decision aid on BRCA1/2 genetic testing in Orthodox Jewish women [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-16.