<p>Self-reported measurements of body size are commonly used in cancer epidemiological studies; however, inaccuracies may lead to misclassification of body mass index (BMI) and biased estimates of associations with health outcomes. Despite their widespread use, the validity of these self-reported measures has not been well established among Hispanic breast cancer survivors, a growing and understudied population. This is particularly important, as prior research suggests that the accuracy of self-reported anthropometric measures may vary across racial and ethnic groups, highlighting the need for population-specific validation. To address this gap, we compared self-reported and measured weight, height, and BMI among 192 Hispanic women participating in the New Jersey Breast Cancer Survivors Study using intraclass correlation coefficients (ICCs), Bland–Altman analyses, and Cohen’s kappa, and examined predictors of reporting error using multivariable regression models. Data were collected during home visits, including body measurements taken by research staff and interviewer-administered questionnaires on body size and related factors. Self-reported and measured values were highly correlated (Intraclass correlation coefficients (95% Confidence Intervals (CI)): 0.99 (0.99, 0.99), 0.8 (0.64, 0.88), 0.95 (0.92, 0.97) for weight, height, and BMI, respectively). The agreement between self-reported and measured BMI categories (normal, overweight, and obese) was strong (kappa: 0.85; 95% CI: 0.79, 0.91). The mean difference observed between self-reported and measured BMI (-0.67&#xa0;kg/m²) was primarily explained by slight over-reporting of height (mean difference: 1.94&#xa0;cm). These findings support the use of self-reported weight, height, and BMI measures in large epidemiologic studies of Hispanic/ Latina cancer survivors when direct measurements are not feasible.</p>