Heterogeneity in breast cancer is related to aggressiveness and poor prognosis. In this study, we evaluated if qualitative visual evaluation and quantitative assessment with histogram analysis of tumor heterogeneity on diffusion weighted imaging (DWI) could be used to predict molecular subtype in invasive breast cancer. We retrospectively evaluated 91 patients with invasive ductal carcinoma. Two radiologists classified the imaging appearance of tumors on DWI according to heterogeneity. The lesions were also evaluated with histogram analysis on apparent diffusion coefficient maps. There was no statistically significant difference on heterogeneity among molecular subtypes on visual evaluation or histogram analysis.