The diffusion time dependence of ADC measurements has been investigated using OGSE and PGSE sequences in human breast tumors. Relative changes in ADC values corresponding to two diffusion times, in addition to ADC values for each diffusion time were calculated in malignant and benign breast lesions as well as in normal breast tissues. Significant differences of ADC changes, in addition to ADC values for each diffusion time, have been found among malignant and benign lesions and normal breast tissue. No ADC changes have been identified in a dedicated breast phantom. ADC maps corresponding to different diffusion times indicate that ADC changes might provide insight in revealing new tissue features like, for instance, intracellular structure of breast tumors.