OBJECTIVES: Non-participation by potential study subjects in population research can affect the validity and generalizability of study outcomes.  The study objectives were to evaluate the differences between participants and non-participants who were targeted for enrollment in the Bonnie’s Bus Mobile Mammography Program (BBMMP) conducted throughout West Virginia, and to determine the predictors of willingness to participate in future research among those who consented to provide initial surveillance data. METHODS: Data collected from 2441 women who were screened in the BBMMP were analyzed using the chi-square test and logistic regression. RESULTS: Of the 2441 women who were screened by BBMMP over a 3 year period, 1178 women (48.3%) chose not to consent to participate in the surveillance study.  Bivariate analysis indicated that being over 65 years, single, overweight, uninsured, unemployed, or of minority race were associated with non-enrollment in the study.  The multivariate adjusted model indicated that being of age 65 years and above (AOR=2.10), being single (AOR=1.25), or being from a minority race (AOR=1.97) were significant predictors of non-participation.  Of the 1,263 women who consented to participate in the study and provided surveillance data, 407 women (32.2%) declined to being contacted for participation in future breast cancer screening research.  The unadjusted model showed that women who have breast problems, are adherent to mammography screening guidelines, and are married/partnered are more likely to be willing to participate in future research.  Multivariate logistic regression analysis revealed that women adherent to mammography screening guidelines are more likely to agree (AOR=1.40) to participate in future research than non adherent women.  CONCLUSIONS: Women who are at risk for breast cancer and who are likely targets for interventions to increase adherence to mammography screening guidelines are more likely to not participate in breast cancer screening studies than  those who may not be at risk and are adherent to screening guidelines.