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Purpose The aim of this study was to evaluate the role of apparent diffusion coefficient (ADC) and hence diffusion-weighted imaging in prediction of pathological complete response (pCR) to neoadjuvant chemotherapy (NACT) in locally advanced breast cancer (LABC) and its molecular subtypes. Methods In this tertiary hospital-based prospective study, 30 patients aged 30 to 65 years, having clinically/cytologically diagnosed LABC, were included. Magnetic resonance imaging (MRI) was done to obtain prechemotherapy ADC (ADC pre), postchemotherapy ADC (ADC post), change in ADC (ΔADC), and ΔADC% for each tumor and its subtype. Postsurgical pCR was used as the reference standard for determining tumor response. All four ADC parameters were compared between pCR and non-pCR groups. Results Of the 30 patients, 19 (63.3%) patients showed pCR, while 11 (36.7%) patients did not. The pCR group showed significantly lower mean ADC pre (p < 0.001) and higher mean ADC post (p < 0.05), ΔADC, and ΔADC% (p = 0.000) than non-pCR group. The best cutoff values to differentiate responders from nonresponders with receiver operating characteristic curve analysis of ADC pre , ADC post , and ΔADC% were 0.98 × 10 −3 mm 2 /s (68.4% sensitivity, 63.6% specificity), 1.31×10 −3 mm 2 /s (68.4% sensitivity, 63.6% specificity), and 25% (84.2% sensitivity, 90.9% specificity), respectively. Human epidermal growth factor receptor 2 (HER2)-enriched subtype showed significant difference in mean ADC pre (p = 0.045), while triple-negative subtype showed significant differences in mean ADC post (p = 0.032) and mean ΔADC (p = 0.019) between the two groups. Conclusion ADC pre , ADC post , and ΔADC can predict pCR to NACT in LABC. Among molecular subtypes, ADC pre was predictive only in HER2-enriched subtype, while ADC post and ΔADC were predictive only in triple-negative subtype. [ABSTRACT FROM AUTHOR]